diff --git a/jps/model-api/src/com/intellij/openapi/fileTypes/ExtensionFileNameMatcher.java b/jps/model-api/src/com/intellij/openapi/fileTypes/ExtensionFileNameMatcher.java
index 6c0a559fa474..2336343df398 100644
--- a/jps/model-api/src/com/intellij/openapi/fileTypes/ExtensionFileNameMatcher.java
+++ b/jps/model-api/src/com/intellij/openapi/fileTypes/ExtensionFileNameMatcher.java
@@ -45,22 +45,23 @@ public class ExtensionFileNameMatcher implements FileNameMatcher {
     return "*." + myExtension;
   }
 
+  @NotNull
   public String getExtension() {
     return myExtension;
   }
 
 
+  @Override
   public boolean equals(final Object o) {
     if (this == o) return true;
     if (o == null || getClass() != o.getClass()) return false;
 
     final ExtensionFileNameMatcher that = (ExtensionFileNameMatcher)o;
 
-    if (!myExtension.equals(that.myExtension)) return false;
-
-    return true;
+    return myExtension.equals(that.myExtension);
   }
 
+  @Override
   public int hashCode() {
     return myExtension.hashCode();
   }
diff --git a/jps/model-impl/src/com/intellij/openapi/fileTypes/impl/FileTypeAssocTable.java b/jps/model-impl/src/com/intellij/openapi/fileTypes/impl/FileTypeAssocTable.java
index 2f92ca6bf26a..9a578034422c 100644
--- a/jps/model-impl/src/com/intellij/openapi/fileTypes/impl/FileTypeAssocTable.java
+++ b/jps/model-impl/src/com/intellij/openapi/fileTypes/impl/FileTypeAssocTable.java
@@ -19,14 +19,14 @@ import java.util.*;
  * @author max
  */
 public class FileTypeAssocTable<T> {
-  private final THashMap<CharSequence, T> myExtensionMappings;
-  private final THashMap<CharSequence, T> myExactFileNameMappings;
-  private final THashMap<CharSequence, T> myExactFileNameAnyCaseMappings;
+  private final Map<CharSequence, T> myExtensionMappings;
+  private final Map<CharSequence, T> myExactFileNameMappings;
+  private final Map<CharSequence, T> myExactFileNameAnyCaseMappings;
   private final List<Pair<FileNameMatcher, T>> myMatchingMappings;
 
-  private FileTypeAssocTable(@NotNull Map<CharSequence, T> extensionMappings,
-                             @NotNull Map<CharSequence, T> exactFileNameMappings,
-                             @NotNull Map<CharSequence, T> exactFileNameAnyCaseMappings,
+  private FileTypeAssocTable(@NotNull Map<? extends CharSequence, ? extends T> extensionMappings,
+                             @NotNull Map<? extends CharSequence, ? extends T> exactFileNameMappings,
+                             @NotNull Map<? extends CharSequence, T> exactFileNameAnyCaseMappings,
                              @NotNull List<? extends Pair<FileNameMatcher, T>> matchingMappings) {
     myExtensionMappings = new THashMap<>(Math.max(10, extensionMappings.size()), 0.5f, CharSequenceHashingStrategy.CASE_INSENSITIVE);
     myExtensionMappings.putAll(extensionMappings);
@@ -90,15 +90,7 @@ public class FileTypeAssocTable<T> {
       return false;
     }
 
-    List<Pair<FileNameMatcher, T>> copy = new ArrayList<>(myMatchingMappings);
-    for (Pair<FileNameMatcher, T> assoc : copy) {
-      if (matcher.equals(assoc.getFirst())) {
-        myMatchingMappings.remove(assoc);
-        return true;
-      }
-    }
-
-    return false;
+    return myMatchingMappings.removeIf(assoc -> matcher.equals(assoc.getFirst()));
   }
 
   boolean removeAllAssociations(@NotNull T type) {
@@ -107,27 +99,11 @@ public class FileTypeAssocTable<T> {
     changed = removeAssociationsFromMap(myExactFileNameAnyCaseMappings, type, changed);
     changed = removeAssociationsFromMap(myExactFileNameMappings, type, changed);
 
-    List<Pair<FileNameMatcher, T>> copy = new ArrayList<>(myMatchingMappings);
-    for (Pair<FileNameMatcher, T> assoc : copy) {
-      if (assoc.getSecond() == type) {
-        myMatchingMappings.remove(assoc);
-        changed = true;
-      }
-    }
-
-    return changed;
+    return myMatchingMappings.removeIf(assoc -> assoc.getSecond() == type);
   }
 
   private boolean removeAssociationsFromMap(@NotNull Map<CharSequence, T> extensionMappings, @NotNull T type, boolean changed) {
-    Set<CharSequence> exts = extensionMappings.keySet();
-    CharSequence[] extsStrings = exts.toArray(new CharSequence[0]);
-    for (CharSequence s : extsStrings) {
-      if (extensionMappings.get(s) == type) {
-        extensionMappings.remove(s);
-        changed = true;
-      }
-    }
-    return changed;
+    return extensionMappings.entrySet().removeIf(entry -> entry.getValue() == type) || changed;
   }
 
   @Nullable
@@ -201,26 +177,21 @@ public class FileTypeAssocTable<T> {
       }
     }
 
-    myExactFileNameMappings.forEachEntry((key, value) -> {
-      if (value == type) {
-        result.add(new ExactFileNameMatcher(key.toString()));
+    for (Map.Entry<CharSequence, T> entry : myExactFileNameMappings.entrySet()) {
+      if (entry.getValue() == type) {
+        result.add(new ExactFileNameMatcher(entry.getKey().toString(), false));
       }
-      return true;
-    });
-
-    myExactFileNameAnyCaseMappings.forEachEntry((key, value) -> {
-      if (value == type) {
-        result.add(new ExactFileNameMatcher(key.toString(), true));
+    }
+    for (Map.Entry<CharSequence, T> entry : myExactFileNameAnyCaseMappings.entrySet()) {
+      if (entry.getValue() == type) {
+        result.add(new ExactFileNameMatcher(entry.getKey().toString(), true));
       }
-      return true;
-    });
-
-    myExtensionMappings.forEachEntry((key, value) -> {
-      if (value == type) {
-        result.add(new ExtensionFileNameMatcher(key.toString()));
+    }
+    for (Map.Entry<CharSequence, T> entry : myExtensionMappings.entrySet()) {
+      if (entry.getValue() == type) {
+        result.add(new ExtensionFileNameMatcher(entry.getKey().toString()));
       }
-      return true;
-    });
+    }
 
     return result;
   }
@@ -239,7 +210,8 @@ public class FileTypeAssocTable<T> {
     return false;
   }
 
-  Map<FileNameMatcher, T> getRemovedMappings(FileTypeAssocTable<T> newTable, Collection<? extends T> keys) {
+  @NotNull
+  Map<FileNameMatcher, T> getRemovedMappings(@NotNull FileTypeAssocTable<T> newTable, @NotNull Collection<? extends T> keys) {
     Map<FileNameMatcher, T> map = new HashMap<>();
     for (T key : keys) {
       List<FileNameMatcher> associations = getAssociations(key);
@@ -251,6 +223,7 @@ public class FileTypeAssocTable<T> {
     return map;
   }
 
+  @Override
   public boolean equals(Object o) {
     if (this == o) {
       return true;
@@ -266,6 +239,7 @@ public class FileTypeAssocTable<T> {
            myExactFileNameAnyCaseMappings.equals(that.myExactFileNameAnyCaseMappings);
   }
 
+  @Override
   public int hashCode() {
     int result = myExtensionMappings.hashCode();
     result = 31 * result + myMatchingMappings.hashCode();
diff --git a/platform/platform-api/src/com/intellij/ui/SimpleListCellRenderer.java b/platform/platform-api/src/com/intellij/ui/SimpleListCellRenderer.java
index 2c0f38589301..40458a14e389 100644
--- a/platform/platform-api/src/com/intellij/ui/SimpleListCellRenderer.java
+++ b/platform/platform-api/src/com/intellij/ui/SimpleListCellRenderer.java
@@ -25,7 +25,7 @@ public abstract class SimpleListCellRenderer<T> extends JBLabel implements ListC
   public static <T> SimpleListCellRenderer<T> create(@NotNull String nullValue, @NotNull Function<? super T, String> getText) {
     return new SimpleListCellRenderer<T>() {
       @Override
-      public void customize(JList<? extends T> list, T value, int index, boolean selected, boolean hasFocus) {
+      public void customize(@NotNull JList<? extends T> list, T value, int index, boolean selected, boolean hasFocus) {
         setText(value == null ? nullValue : getText.fun(value));
       }
     };
@@ -35,7 +35,7 @@ public abstract class SimpleListCellRenderer<T> extends JBLabel implements ListC
   public static <T> SimpleListCellRenderer<T> create(@NotNull Customizer<? super T> customizer) {
     return new SimpleListCellRenderer<T>() {
       @Override
-      public void customize(JList<? extends T> list, T value, int index, boolean selected, boolean hasFocus) {
+      public void customize(@NotNull JList<? extends T> list, T value, int index, boolean selected, boolean hasFocus) {
         customizer.customize(this, value, index);
       }
     };
@@ -66,7 +66,7 @@ public abstract class SimpleListCellRenderer<T> extends JBLabel implements ListC
     return this;
   }
 
-  public abstract void customize(JList<? extends T> list, T value, int index, boolean selected, boolean hasFocus);
+  public abstract void customize(@NotNull JList<? extends T> list, T value, int index, boolean selected, boolean hasFocus);
 
   @Override
   public Dimension getPreferredSize() {
diff --git a/platform/platform-impl/src/com/intellij/openapi/fileTypes/impl/AbstractFileType.java b/platform/platform-impl/src/com/intellij/openapi/fileTypes/impl/AbstractFileType.java
index 92f89ac63600..3b42bceddb2d 100644
--- a/platform/platform-impl/src/com/intellij/openapi/fileTypes/impl/AbstractFileType.java
+++ b/platform/platform-impl/src/com/intellij/openapi/fileTypes/impl/AbstractFileType.java
@@ -34,7 +34,7 @@ public class AbstractFileType extends UserFileType<AbstractFileType> implements
   private static final String SEMICOLON = ";";
   protected SyntaxTable mySyntaxTable;
   private SyntaxTable myDefaultSyntaxTable;
-  protected Commenter myCommenter = null;
+  protected Commenter myCommenter;
   @NonNls public static final String ELEMENT_HIGHLIGHTING = "highlighting";
   @NonNls private static final String ELEMENT_OPTIONS = "options";
   @NonNls private static final String ELEMENT_OPTION = "option";
@@ -62,7 +62,7 @@ public class AbstractFileType extends UserFileType<AbstractFileType> implements
     mySyntaxTable = syntaxTable;
   }
 
-  public void initSupport() {
+  void initSupport() {
     for (FileTypeRegistrator registrator : Extensions.getRootArea().getExtensionPoint(FileTypeRegistrator.EP_NAME).getExtensions()) {
       registrator.initFileType(this);
     }
@@ -109,7 +109,7 @@ public class AbstractFileType extends UserFileType<AbstractFileType> implements
   }
 
   @NotNull
-  public static SyntaxTable readSyntaxTable(@NotNull Element root) {
+  static SyntaxTable readSyntaxTable(@NotNull Element root) {
     SyntaxTable table = new SyntaxTable();
 
     for (Element element : root.getChildren()) {
@@ -186,7 +186,7 @@ public class AbstractFileType extends UserFileType<AbstractFileType> implements
       StringTokenizer tokenizer = new StringTokenizer(value, SEMICOLON);
       while(tokenizer.hasMoreElements()) {
         String keyword = tokenizer.nextToken().trim();
-        if (keyword.length() != 0) keywords.add(keyword);
+        if (!keyword.isEmpty()) keywords.add(keyword);
       }
     }
     for (final Object o1 : element.getChildren(ELEMENT_KEYWORD)) {
@@ -272,7 +272,7 @@ public class AbstractFileType extends UserFileType<AbstractFileType> implements
   }
 
   private static Element writeKeywords(Set<String> keywords, String tagName, Element highlightingElement) {
-    if (keywords.size() == 0 && !ELEMENT_KEYWORDS.equals(tagName)) return null;
+    if (keywords.isEmpty() && !ELEMENT_KEYWORDS.equals(tagName)) return null;
     Element keywordsElement = new Element(tagName);
     String[] strings = ArrayUtilRt.toStringArray(keywords);
     Arrays.sort(strings);
@@ -311,7 +311,7 @@ public class AbstractFileType extends UserFileType<AbstractFileType> implements
   @NonNls static final String ATTRIBUTE_TYPE = "type";
 
   @NotNull
-  public static List<Pair<FileNameMatcher, String>> readAssociations(@NotNull Element element) {
+  static List<Pair<FileNameMatcher, String>> readAssociations(@NotNull Element element) {
     List<Element> children = element.getChildren(ELEMENT_MAPPING);
     if (children.isEmpty()) {
       return Collections.emptyList();
@@ -329,7 +329,7 @@ public class AbstractFileType extends UserFileType<AbstractFileType> implements
   }
 
   @Nullable
-  public static Element writeMapping(String typeName, @NotNull FileNameMatcher matcher, boolean specifyTypeName) {
+  static Element writeMapping(String typeName, @NotNull FileNameMatcher matcher, boolean specifyTypeName) {
     Element mapping = new Element(ELEMENT_MAPPING);
     if (matcher instanceof ExtensionFileNameMatcher) {
       mapping.setAttribute(ATTRIBUTE_EXT, ((ExtensionFileNameMatcher)matcher).getExtension());
diff --git a/platform/platform-impl/src/com/intellij/openapi/fileTypes/impl/FileTypeBean.java b/platform/platform-impl/src/com/intellij/openapi/fileTypes/impl/FileTypeBean.java
index 62b6f21cccfc..f8f3253f021d 100644
--- a/platform/platform-impl/src/com/intellij/openapi/fileTypes/impl/FileTypeBean.java
+++ b/platform/platform-impl/src/com/intellij/openapi/fileTypes/impl/FileTypeBean.java
@@ -70,7 +70,7 @@ public class FileTypeBean extends AbstractExtensionPointBean {
   public String language;
 
   @ApiStatus.Internal
-  public void addMatchers(List<FileNameMatcher> matchers) {
+  public void addMatchers(List<? extends FileNameMatcher> matchers) {
     myMatchers.addAll(matchers);
   }
 
diff --git a/platform/platform-impl/src/com/intellij/openapi/fileTypes/impl/FileTypeManagerImpl.java b/platform/platform-impl/src/com/intellij/openapi/fileTypes/impl/FileTypeManagerImpl.java
index b8d346f38768..bc66842012aa 100644
--- a/platform/platform-impl/src/com/intellij/openapi/fileTypes/impl/FileTypeManagerImpl.java
+++ b/platform/platform-impl/src/com/intellij/openapi/fileTypes/impl/FileTypeManagerImpl.java
@@ -157,8 +157,8 @@ public class FileTypeManagerImpl extends FileTypeManagerEx implements Persistent
 
   private final Object PENDING_INIT_LOCK = new Object();
 
-  private MultiValuesMap<FileType, FileTypeDetector> myFileTypeDetectorMap = null;
-  private List<FileTypeDetector> myUntypedFileTypeDetectors = new ArrayList<>();
+  private MultiValuesMap<FileType, FileTypeDetector> myFileTypeDetectorMap;
+  private final List<FileTypeDetector> myUntypedFileTypeDetectors = new ArrayList<>();
   private final Object FILE_TYPE_DETECTOR_MAP_LOCK = new Object();
 
   public FileTypeManagerImpl() {
@@ -377,9 +377,9 @@ public class FileTypeManagerImpl extends FileTypeManagerEx implements Persistent
     for (FileTypeBean bean : fileTypeBeans) {
       bean.addMatchers(ContainerUtil.concat(
         parse(bean.extensions),
-        parse(bean.fileNames, (token) -> new ExactFileNameMatcher(token)),
-        parse(bean.fileNamesCaseInsensitive, (token) -> new ExactFileNameMatcher(token, true)),
-        parse(bean.patterns, (token) -> FileNameMatcherFactory.getInstance().createMatcher(token))));
+        parse(bean.fileNames, token -> new ExactFileNameMatcher(token)),
+        parse(bean.fileNamesCaseInsensitive, token -> new ExactFileNameMatcher(token, true)),
+        parse(bean.patterns, token -> FileNameMatcherFactory.getInstance().createMatcher(token))));
     }
 
     for (FileTypeBean bean : fileTypeBeans) {
@@ -920,7 +920,7 @@ public class FileTypeManagerImpl extends FileTypeManagerEx implements Persistent
   }
 
   @NotNull
-  private FileType detectFromContent(@NotNull VirtualFile file, @NotNull Iterable<FileTypeDetector> detectors) throws IOException {
+  private FileType detectFromContent(@NotNull VirtualFile file, @NotNull Iterable<? extends FileTypeDetector> detectors) throws IOException {
     FileType fileType;
     try (InputStream inputStream = ((FileSystemInterface)file.getFileSystem()).getInputStream(file)) {
       if (toLog()) {
@@ -956,7 +956,7 @@ public class FileTypeManagerImpl extends FileTypeManagerEx implements Persistent
   }
 
   @NotNull
-  private FileType detect(@NotNull VirtualFile file, @NotNull byte[] bytes, int length, @NotNull Iterable<FileTypeDetector> detectors) {
+  private FileType detect(@NotNull VirtualFile file, @NotNull byte[] bytes, int length, @NotNull Iterable<? extends FileTypeDetector> detectors) {
     if (length <= 0) return UnknownFileType.INSTANCE;
 
     // use PlainTextFileType because it doesn't supply its own charset detector
@@ -1095,7 +1095,7 @@ public class FileTypeManagerImpl extends FileTypeManagerEx implements Persistent
           return true;
         }
       }
-      catch (IOException ignored) { ;
+      catch (IOException ignored) {
       }
     }
 
@@ -1526,7 +1526,7 @@ public class FileTypeManagerImpl extends FileTypeManagerEx implements Persistent
   }
 
   @NotNull
-  private static List<FileNameMatcher> parse(@Nullable String semicolonDelimited, Function<String, FileNameMatcher> matcherFactory) {
+  private static List<FileNameMatcher> parse(@Nullable String semicolonDelimited, Function<? super String, ? extends FileNameMatcher> matcherFactory) {
     if (semicolonDelimited == null) {
       return Collections.emptyList();
     }
@@ -1669,7 +1669,7 @@ public class FileTypeManagerImpl extends FileTypeManagerEx implements Persistent
     return myPatternsTable;
   }
 
-  void setPatternsTable(@NotNull Set<FileType> fileTypes, @NotNull FileTypeAssocTable<FileType> assocTable) {
+  void setPatternsTable(@NotNull Set<? extends FileType> fileTypes, @NotNull FileTypeAssocTable<FileType> assocTable) {
     Map<FileNameMatcher, FileType> removedMappings = getExtensionMap().getRemovedMappings(assocTable, fileTypes);
     fireBeforeFileTypesChanged();
     for (FileType existing : getRegisteredFileTypes()) {
@@ -1690,8 +1690,8 @@ public class FileTypeManagerImpl extends FileTypeManagerEx implements Persistent
       FileType fileType = getFileTypeByName(fileTypeName);
       return fileType != null && assocTable.isAssociatedWith(fileType, matcher);
     });
-    for (FileNameMatcher matcher : removedMappings.keySet()) {
-      myRemovedMappingTracker.add(matcher, removedMappings.get(matcher).getName(), true);
+    for (Map.Entry<FileNameMatcher, FileType> entry : removedMappings.entrySet()) {
+      myRemovedMappingTracker.add(entry.getKey(), entry.getValue().getName(), true);
     }
   }
 
@@ -1748,7 +1748,7 @@ public class FileTypeManagerImpl extends FileTypeManagerEx implements Persistent
     }
   }
 
-  private void registerReDetectedMapping(String fileTypeName, @NotNull FileNameMatcher matcher) {
+  private void registerReDetectedMapping(@NotNull String fileTypeName, @NotNull FileNameMatcher matcher) {
     String typeName = myUnresolvedMappings.get(matcher);
     if (typeName != null && !typeName.equals(fileTypeName)) {
       if (!myRemovedMappingTracker.hasRemovedMapping(matcher)) {
diff --git a/platform/platform-impl/src/com/intellij/openapi/fileTypes/impl/FileTypeRenderer.java b/platform/platform-impl/src/com/intellij/openapi/fileTypes/impl/FileTypeRenderer.java
index 748978e9c0a9..fc36b3950d42 100644
--- a/platform/platform-impl/src/com/intellij/openapi/fileTypes/impl/FileTypeRenderer.java
+++ b/platform/platform-impl/src/com/intellij/openapi/fileTypes/impl/FileTypeRenderer.java
@@ -19,6 +19,7 @@ public class FileTypeRenderer extends SimpleListCellRenderer<FileType> {
   private static final Pattern CLEANUP = Pattern.compile("(?i)\\s+file(?:s)?$");
 
   public interface FileTypeListProvider {
+    @NotNull
     Iterable<FileType> getCurrentFileTypeList();
   }
 
@@ -29,12 +30,11 @@ public class FileTypeRenderer extends SimpleListCellRenderer<FileType> {
   }
 
   public FileTypeRenderer(@NotNull FileTypeListProvider fileTypeListProvider) {
-    super();
     myFileTypeListProvider = fileTypeListProvider;
   }
 
   @Override
-  public void customize(JList<? extends FileType> list, FileType value, int index, boolean selected, boolean hasFocus) {
+  public void customize(@NotNull JList<? extends FileType> list, FileType value, int index, boolean selected, boolean hasFocus) {
     LayeredIcon layeredIcon = new LayeredIcon(2);
     layeredIcon.setIcon(EMPTY_ICON, 0);
     Icon icon = value.getIcon();
@@ -54,7 +54,7 @@ public class FileTypeRenderer extends SimpleListCellRenderer<FileType> {
     }
   }
 
-  private boolean isDuplicated(final String description) {
+  private boolean isDuplicated(@NotNull String description) {
     boolean found = false;
 
     for (FileType type : myFileTypeListProvider.getCurrentFileTypeList()) {
@@ -71,12 +71,9 @@ public class FileTypeRenderer extends SimpleListCellRenderer<FileType> {
   }
 
   private static class DefaultFileTypeListProvider implements FileTypeListProvider {
-    private final List<FileType> myFileTypes;
-
-    DefaultFileTypeListProvider() {
-      myFileTypes = Arrays.asList(FileTypeManager.getInstance().getRegisteredFileTypes());
-    }
+    private final List<FileType> myFileTypes = Arrays.asList(FileTypeManager.getInstance().getRegisteredFileTypes());
 
+    @NotNull
     @Override
     public Iterable<FileType> getCurrentFileTypeList() {
       return myFileTypes;
diff --git a/platform/platform-impl/src/com/intellij/openapi/fileTypes/impl/IgnoredFileCache.java b/platform/platform-impl/src/com/intellij/openapi/fileTypes/impl/IgnoredFileCache.java
index 91ed53833865..33702d8b7ec8 100644
--- a/platform/platform-impl/src/com/intellij/openapi/fileTypes/impl/IgnoredFileCache.java
+++ b/platform/platform-impl/src/com/intellij/openapi/fileTypes/impl/IgnoredFileCache.java
@@ -59,7 +59,7 @@ final class IgnoredFileCache {
     myNonIgnoredIds.clear();
   }
 
-  boolean isFileIgnored(VirtualFile file) {
+  boolean isFileIgnored(@NotNull VirtualFile file) {
     int id = myVfsEventNesting == 0 && file instanceof NewVirtualFile ? ((NewVirtualFile)file).getId() : -1;
     if (id > 0 && myNonIgnoredIds.get(id)) {
       return false;
diff --git a/platform/platform-impl/src/com/intellij/openapi/fileTypes/impl/RemovedMappingTracker.java b/platform/platform-impl/src/com/intellij/openapi/fileTypes/impl/RemovedMappingTracker.java
index 7760a3d086c1..86e5b35c6cc6 100644
--- a/platform/platform-impl/src/com/intellij/openapi/fileTypes/impl/RemovedMappingTracker.java
+++ b/platform/platform-impl/src/com/intellij/openapi/fileTypes/impl/RemovedMappingTracker.java
@@ -17,7 +17,7 @@ class RemovedMappingTracker {
     private final String myFileTypeName;
     private boolean myApproved;
 
-    private RemovedMapping(FileNameMatcher matcher, String name, boolean approved) {
+    private RemovedMapping(@NotNull FileNameMatcher matcher, @NotNull String name, boolean approved) {
       myFileNameMatcher = matcher;
       myFileTypeName = name;
       myApproved = approved;
@@ -45,13 +45,13 @@ class RemovedMappingTracker {
   @NonNls private static final String ELEMENT_REMOVED_MAPPING = "removed_mapping";
   /** Applied for removed mappings approved by user */
   @NonNls private static final String ATTRIBUTE_APPROVED = "approved";
-  @NonNls static final String ATTRIBUTE_TYPE = "type";
+  @NonNls private static final String ATTRIBUTE_TYPE = "type";
 
   void clear() {
     myRemovedMappings.clear();
   }
 
-  public void add(FileNameMatcher matcher, String fileTypeName, boolean approved) {
+  public void add(@NotNull FileNameMatcher matcher, @NotNull String fileTypeName, boolean approved) {
     myRemovedMappings.put(matcher, new RemovedMapping(matcher, fileTypeName, approved));
   }
 
@@ -71,7 +71,9 @@ class RemovedMappingTracker {
     List<RemovedMapping> result = new ArrayList<>();
     for (Element mapping : children) {
       String ext = mapping.getAttributeValue(AbstractFileType.ATTRIBUTE_EXT);
-      FileNameMatcher matcher = ext == null ? FileTypeManager.parseFromString(mapping.getAttributeValue(AbstractFileType.ATTRIBUTE_PATTERN)) : new ExtensionFileNameMatcher(ext);
+      FileNameMatcher matcher = ext == null
+                                ? FileTypeManager.parseFromString(mapping.getAttributeValue(AbstractFileType.ATTRIBUTE_PATTERN))
+                                : new ExtensionFileNameMatcher(ext);
       boolean approved = Boolean.parseBoolean(mapping.getAttributeValue(ATTRIBUTE_APPROVED));
       String fileTypeName = mapping.getAttributeValue(ATTRIBUTE_TYPE);
       if (fileTypeName == null) continue;
@@ -82,7 +84,7 @@ class RemovedMappingTracker {
     return result;
   }
 
-  public void save(Element element) {
+  public void save(@NotNull Element element) {
     for (RemovedMapping mapping : myRemovedMappings.values()) {
       Element content = writeRemovedMapping(mapping.myFileTypeName, mapping.myFileNameMatcher, true, mapping.myApproved);
       if (content != null) {
@@ -91,7 +93,7 @@ class RemovedMappingTracker {
     }
   }
 
-  public void saveRemovedMappingsForFileType(Element map, String fileTypeName, Set<FileNameMatcher> associations, boolean specifyTypeName) {
+  void saveRemovedMappingsForFileType(@NotNull Element map, @NotNull String fileTypeName, @NotNull Set<? extends FileNameMatcher> associations, boolean specifyTypeName) {
     for (FileNameMatcher matcher : associations) {
       Element content = writeRemovedMapping(fileTypeName, matcher, specifyTypeName, isApproved(matcher));
       if (content != null) {
@@ -100,24 +102,25 @@ class RemovedMappingTracker {
     }
   }
 
-  boolean hasRemovedMapping(FileNameMatcher matcher) {
+  boolean hasRemovedMapping(@NotNull FileNameMatcher matcher) {
     return myRemovedMappings.containsKey(matcher);
   }
 
-  boolean isApproved(FileNameMatcher matcher) {
+  private boolean isApproved(@NotNull FileNameMatcher matcher) {
     RemovedMapping mapping = myRemovedMappings.get(matcher);
     return mapping != null && mapping.isApproved();
    }
 
-  public void approveRemoval(String fileTypeName, FileNameMatcher matcher) {
+  void approveRemoval(@NotNull String fileTypeName, @NotNull FileNameMatcher matcher) {
     myRemovedMappings.put(matcher, new RemovedMapping(matcher, fileTypeName, true));
   }
 
+  @NotNull
   public List<RemovedMapping> getRemovedMappings() {
     return new ArrayList<>(myRemovedMappings.values());
   }
 
-  public List<FileNameMatcher> getMappingsForFileType(String name) {
+  List<FileNameMatcher> getMappingsForFileType(@NotNull String name) {
     List<FileNameMatcher> result = new ArrayList<>();
     for (RemovedMapping mapping : myRemovedMappings.values()) {
       if (mapping.myFileTypeName.equals(name)) {
@@ -127,15 +130,11 @@ class RemovedMappingTracker {
     return result;
   }
 
-  void removeMatching(BiPredicate<FileNameMatcher, String> predicate) {
-    for (Iterator<Map.Entry<FileNameMatcher, RemovedMapping>> it = myRemovedMappings.entrySet().iterator(); it.hasNext(); ) {
-      Map.Entry<FileNameMatcher, RemovedMapping> next = it.next();
-      if (predicate.test(next.getValue().myFileNameMatcher, next.getValue().myFileTypeName)) {
-        it.remove();
-      }
-    }
+  void removeMatching(@NotNull BiPredicate<? super FileNameMatcher, ? super String> predicate) {
+    myRemovedMappings.entrySet().removeIf(next -> predicate.test(next.getValue().myFileNameMatcher, next.getValue().myFileTypeName));
   }
 
+  @NotNull
   List<RemovedMapping> retrieveUnapprovedMappings() {
     List<RemovedMapping> result = new ArrayList<>();
     for (Iterator<Map.Entry<FileNameMatcher, RemovedMapping>> it = myRemovedMappings.entrySet().iterator(); it.hasNext(); ) {
@@ -148,10 +147,10 @@ class RemovedMappingTracker {
     return result;
   }
 
-  static Element writeRemovedMapping(@NotNull String fileTypeName,
-                                     @NotNull FileNameMatcher matcher,
-                                     boolean specifyTypeName,
-                                     boolean approved) {
+  private static Element writeRemovedMapping(@NotNull String fileTypeName,
+                                             @NotNull FileNameMatcher matcher,
+                                             boolean specifyTypeName,
+                                             boolean approved) {
     Element mapping = new Element(ELEMENT_REMOVED_MAPPING);
     if (matcher instanceof ExtensionFileNameMatcher) {
       mapping.setAttribute(AbstractFileType.ATTRIBUTE_EXT, ((ExtensionFileNameMatcher)matcher).getExtension());
diff --git a/platform/platform-tests/testSrc/com/intellij/util/concurrency/AppScheduledExecutorServiceTest.java b/platform/platform-tests/testSrc/com/intellij/util/concurrency/AppScheduledExecutorServiceTest.java
index 60d023f961bc..143b4565f578 100644
--- a/platform/platform-tests/testSrc/com/intellij/util/concurrency/AppScheduledExecutorServiceTest.java
+++ b/platform/platform-tests/testSrc/com/intellij/util/concurrency/AppScheduledExecutorServiceTest.java
@@ -111,8 +111,8 @@ public class AppScheduledExecutorServiceTest extends TestCase {
 
     assertEquals(4, log.size());
     assertEquals(4, log.get(0).runnable);
-    List<Thread> threads = Arrays.asList(log.get(1).currentThread, log.get(2).currentThread, log.get(3).currentThread);
-    assertEquals(log.toString(), 3, new HashSet<>(threads).size()); // must be executed in parallel
+    Set<Thread> threads = ContainerUtil.map2Set(log, l->l.currentThread);
+    assertEquals(log.toString(), 3, threads.size()); // must be executed in parallel
   }
 
   public void testMustNotBeAbleToShutdown() {
@@ -211,7 +211,7 @@ public class AppScheduledExecutorServiceTest extends TestCase {
       assertEquals(1, service.getBackendPoolExecutorSize());
 
       assertEquals(3, log.size());
-      Set<Thread> usedThreads = new HashSet<>(Arrays.asList(log.get(0).currentThread, log.get(1).currentThread, log.get(2).currentThread));
+      Set<Thread> usedThreads = ContainerUtil.map2Set(log, l->l.currentThread);
       assertEquals(usedThreads.toString(), 1, usedThreads.size()); // must be executed in same thread
     }
     catch (AssertionError e) {
@@ -239,7 +239,7 @@ public class AppScheduledExecutorServiceTest extends TestCase {
     }
 
     assertEquals(N, log.size());
-    Set<Thread> usedThreads = ContainerUtil.map2Set(log, logInfo -> logInfo.currentThread);
+    Set<Thread> usedThreads = ContainerUtil.map2Set(log, l -> l.currentThread);
 
     assertEquals(N, usedThreads.size());
   }