diff --git a/platform/core-api/src/com/intellij/openapi/util/BuildNumber.java b/platform/core-api/src/com/intellij/openapi/util/BuildNumber.java
index 322954c1cdbf..c1061d69c387 100644
--- a/platform/core-api/src/com/intellij/openapi/util/BuildNumber.java
+++ b/platform/core-api/src/com/intellij/openapi/util/BuildNumber.java
@@ -29,8 +29,8 @@ public class BuildNumber implements Comparable<BuildNumber> {
 
   public static final int SNAPSHOT_VALUE = Integer.MAX_VALUE;
 
-  private final @NotNull String myProductCode;
-  private final @NotNull int[] myComponents;
+  @NotNull private final String myProductCode;
+  @NotNull private final int[] myComponents;
 
   public BuildNumber(@NotNull String productCode, int baselineVersion, int buildNumber) {
     this(productCode, new int[]{baselineVersion, buildNumber});
@@ -41,7 +41,8 @@ public class BuildNumber implements Comparable<BuildNumber> {
     myComponents = components;
   }
 
-  public @NotNull String getProductCode() {
+  @NotNull
+  public String getProductCode() {
     return myProductCode;
   }
 
@@ -49,7 +50,8 @@ public class BuildNumber implements Comparable<BuildNumber> {
     return myComponents[0];
   }
 
-  public @NotNull int[] getComponents() {
+  @NotNull
+  public int[] getComponents() {
     return myComponents.clone();
   }
 
@@ -57,23 +59,28 @@ public class BuildNumber implements Comparable<BuildNumber> {
     return ArrayUtil.indexOf(myComponents, SNAPSHOT_VALUE) >= 0;
   }
 
+  @NotNull
   @Contract(pure = true)
-  public @NotNull BuildNumber withoutProductCode() {
+  public BuildNumber withoutProductCode() {
     return myProductCode.isEmpty() ? this : new BuildNumber("", myComponents);
   }
 
+  @NotNull
   public String asString() {
     return asString(true, true);
   }
 
+  @NotNull
   public String asStringWithoutProductCode() {
     return asString(false, true);
   }
 
+  @NotNull
   public String asStringWithoutProductCodeAndSnapshot() {
     return asString(false, false);
   }
 
+  @NotNull
   private String asString(boolean includeProductCode, boolean withSnapshotMarker) {
     StringBuilder builder = new StringBuilder();
 
@@ -99,7 +106,7 @@ public class BuildNumber implements Comparable<BuildNumber> {
     return fromString(version, null, null);
   }
 
-  public static BuildNumber fromStringWithProductCode(String version, String productCode) {
+  public static BuildNumber fromStringWithProductCode(String version, @NotNull String productCode) {
     return fromString(version, null, productCode);
   }
 
@@ -122,8 +129,6 @@ public class BuildNumber implements Comparable<BuildNumber> {
     }
 
     int baselineVersionSeparator = code.indexOf('.');
-    int baselineVersion;
-    int buildNumber;
 
     if (baselineVersionSeparator > 0) {
       String baselineVersionString = code.substring(0, baselineVersionSeparator);
@@ -142,18 +147,18 @@ public class BuildNumber implements Comparable<BuildNumber> {
       return new BuildNumber(productCode, intComponents);
     }
     else {
-      buildNumber = parseBuildNumber(version, code, pluginName);
+      int buildNumber = parseBuildNumber(version, code, pluginName);
       if (buildNumber <= 2000) {
         // it's probably a baseline, not a build number
         return new BuildNumber(productCode, buildNumber, 0);
       }
 
-      baselineVersion = getBaseLineForHistoricBuilds(buildNumber);
+      int baselineVersion = getBaseLineForHistoricBuilds(buildNumber);
       return new BuildNumber(productCode, baselineVersion, buildNumber);
     }
   }
 
-  private static int parseBuildNumber(String version, String code, String pluginName) {
+  private static int parseBuildNumber(String version, @NotNull String code, String pluginName) {
     if (SNAPSHOT.equals(code) || BUILD_NUMBER_PLACEHOLDERS.contains(code) || STAR.equals(code)) {
       return SNAPSHOT_VALUE;
     }
@@ -190,9 +195,7 @@ public class BuildNumber implements Comparable<BuildNumber> {
     BuildNumber that = (BuildNumber)o;
 
     if (!myProductCode.equals(that.myProductCode)) return false;
-    if (!Arrays.equals(myComponents, that.myComponents)) return false;
-
-    return true;
+    return Arrays.equals(myComponents, that.myComponents);
   }
 
   @Override
diff --git a/platform/core-impl/src/com/intellij/ide/plugins/PluginManagerCore.java b/platform/core-impl/src/com/intellij/ide/plugins/PluginManagerCore.java
index 5b590fbedc2c..e10da34b0df2 100644
--- a/platform/core-impl/src/com/intellij/ide/plugins/PluginManagerCore.java
+++ b/platform/core-impl/src/com/intellij/ide/plugins/PluginManagerCore.java
@@ -8,6 +8,7 @@ import com.intellij.ide.StartupProgress;
 import com.intellij.ide.plugins.cl.PluginClassLoader;
 import com.intellij.openapi.application.Application;
 import com.intellij.openapi.application.ApplicationManager;
+import com.intellij.openapi.application.JetBrainsProtocolHandler;
 import com.intellij.openapi.application.PathManager;
 import com.intellij.openapi.application.ex.ApplicationInfoEx;
 import com.intellij.openapi.application.impl.ApplicationInfoImpl;
@@ -51,7 +52,6 @@ import java.util.concurrent.CopyOnWriteArrayList;
 import java.util.zip.ZipEntry;
 import java.util.zip.ZipFile;
 
-import static com.intellij.openapi.application.JetBrainsProtocolHandler.REQUIRED_PLUGINS_KEY;
 import static com.intellij.util.ObjectUtils.notNull;
 import static java.util.Collections.singletonList;
 
@@ -85,7 +85,7 @@ public class PluginManagerCore {
   private static List<String> ourDisabledPlugins;
   private static MultiMap<String, String> ourBrokenPluginVersions;
   private static IdeaPluginDescriptor[] ourPlugins;
-  private static boolean ourUnitTestWithBundledPlugins = false;
+  private static boolean ourUnitTestWithBundledPlugins;
 
   static String myPluginError;
   static List<String> myPlugins2Disable;
@@ -137,7 +137,7 @@ public class PluginManagerCore {
     File file = new File(configPath, DISABLED_PLUGINS_FILENAME);
     if (file.isFile()) {
       ApplicationInfoEx appInfo = ApplicationInfoImpl.getShadowInstance();
-      List<String> requiredPlugins = StringUtil.split(System.getProperty(REQUIRED_PLUGINS_KEY, ""), ",");
+      List<String> requiredPlugins = StringUtil.split(System.getProperty(JetBrainsProtocolHandler.REQUIRED_PLUGINS_KEY, ""), ",");
       try {
         boolean updateDisablePluginsList = false;
         try (BufferedReader reader = new BufferedReader(new FileReader(file))) {
@@ -429,8 +429,7 @@ public class PluginManagerCore {
     return loadPlugins == null || Boolean.TRUE.toString().equals(loadPlugins);
   }
 
-  // used in upsource
-  public static void configureExtensions() {
+  private static void configureExtensions() {
     Extensions.registerAreaClass(ExtensionAreas.IDEA_PROJECT, null);
     Extensions.registerAreaClass(ExtensionAreas.IDEA_MODULE, ExtensionAreas.IDEA_PROJECT);
   }
@@ -879,9 +878,9 @@ public class PluginManagerCore {
     return false;
   }
 
-  public static void resolveOptionalDescriptors(@NotNull String fileName,
-                                                @NotNull IdeaPluginDescriptorImpl descriptor,
-                                                @NotNull Function<? super String, ? extends IdeaPluginDescriptorImpl> optionalDescriptorLoader) {
+  private static void resolveOptionalDescriptors(@NotNull String fileName,
+                                                 @NotNull IdeaPluginDescriptorImpl descriptor,
+                                                 @NotNull Function<? super String, ? extends IdeaPluginDescriptorImpl> optionalDescriptorLoader) {
     Map<PluginId, List<String>> optionalConfigs = descriptor.getOptionalConfigs();
     if (optionalConfigs != null && !optionalConfigs.isEmpty()) {
       Map<PluginId, List<IdeaPluginDescriptorImpl>> descriptors = new THashMap<>(optionalConfigs.size());
@@ -1067,7 +1066,7 @@ public class PluginManagerCore {
         descriptor.setUseCoreClassLoader(true);
         result.add(descriptor);
         if (progress != null && !SPECIAL_IDEA_PLUGIN.equals(descriptor.getName())) {
-          progress.showProgress("Plugin loaded: " + descriptor.getName(), PLUGINS_PROGRESS_PART * (float)(++i) / urls.size());
+          progress.showProgress("Plugin loaded: " + descriptor.getName(), PLUGINS_PROGRESS_PART * (++i) / urls.size());
         }
       }
     }
@@ -1153,8 +1152,8 @@ public class PluginManagerCore {
     return topoSortPlugins(result, errors);
   }
 
-  @NotNull // used in upsource
-  public static IdeaPluginDescriptorImpl[] topoSortPlugins(@NotNull List<IdeaPluginDescriptorImpl> result, @NotNull List<? super String> errors) {
+  @NotNull
+  private static IdeaPluginDescriptorImpl[] topoSortPlugins(@NotNull List<IdeaPluginDescriptorImpl> result, @NotNull List<? super String> errors) {
     IdeaPluginDescriptorImpl[] pluginDescriptors = result.toArray(IdeaPluginDescriptorImpl.EMPTY_ARRAY);
 
     Map<PluginId, IdeaPluginDescriptorImpl> idToDescriptorMap = new THashMap<>();
@@ -1372,7 +1371,7 @@ public class PluginManagerCore {
       }
 
       if (progress != null) {
-        progress.showProgress("", PLUGINS_PROGRESS_PART + (i++ / (float)result.size()) * LOADERS_PROGRESS_PART);
+        progress.showProgress("", PLUGINS_PROGRESS_PART + i++ / (float)result.size() * LOADERS_PROGRESS_PART);
       }
     }
 
@@ -1390,14 +1389,13 @@ public class PluginManagerCore {
     ourPlugins = pluginDescriptors;
   }
 
-  // used in upsource
-  public static void fixDescriptors(@NotNull IdeaPluginDescriptorImpl[] pluginDescriptors,
-                                    @NotNull ClassLoader parentLoader,
-                                    @NotNull Map<PluginId, IdeaPluginDescriptorImpl> idToDescriptorMap,
-                                    @NotNull Map<String, String> disabledPluginNames,
-                                    @NotNull List<? super String> brokenPluginsList,
-                                    @NotNull List<IdeaPluginDescriptorImpl> result,
-                                    @NotNull List<? super String> errors) {
+  private static void fixDescriptors(@NotNull IdeaPluginDescriptorImpl[] pluginDescriptors,
+                                     @NotNull ClassLoader parentLoader,
+                                     @NotNull Map<PluginId, IdeaPluginDescriptorImpl> idToDescriptorMap,
+                                     @NotNull Map<String, String> disabledPluginNames,
+                                     @NotNull List<? super String> brokenPluginsList,
+                                     @NotNull List<IdeaPluginDescriptorImpl> result,
+                                     @NotNull List<? super String> errors) {
     checkCanLoadPlugins(pluginDescriptors, parentLoader, disabledPluginNames, brokenPluginsList, result);
 
     filterBadPlugins(result, disabledPluginNames, errors);
diff --git a/platform/platform-impl/src/com/intellij/concurrency/JobLauncherImpl.java b/platform/platform-impl/src/com/intellij/concurrency/JobLauncherImpl.java
index 65ba75231614..221d6a87d54d 100644
--- a/platform/platform-impl/src/com/intellij/concurrency/JobLauncherImpl.java
+++ b/platform/platform-impl/src/com/intellij/concurrency/JobLauncherImpl.java
@@ -66,7 +66,7 @@ public class JobLauncherImpl extends JobLauncher {
       // call checkCanceled a bit more often than .invoke()
       while (!applier.isDone()) {
         ProgressManager.checkCanceled();
-        // does automatic compensation against starvation
+        // does automatic compensation against starvation (in ForkJoinPool.awaitJoin)
         try {
           applier.get(1, TimeUnit.MILLISECONDS);
         }
diff --git a/platform/platform-impl/src/com/intellij/ide/plugins/PluginInstaller.java b/platform/platform-impl/src/com/intellij/ide/plugins/PluginInstaller.java
index 25ab00c62366..761873d0a332 100644
--- a/platform/platform-impl/src/com/intellij/ide/plugins/PluginInstaller.java
+++ b/platform/platform-impl/src/com/intellij/ide/plugins/PluginInstaller.java
@@ -132,7 +132,7 @@ public class PluginInstaller {
     installedDependant.add(pluginNode);
 
     // check for dependent plugins at first.
-    if (pluginNode.getDepends() != null && pluginNode.getDepends().size() > 0) {
+    if (pluginNode.getDepends() != null && !pluginNode.getDepends().isEmpty()) {
       // prepare plugins list for install
       final PluginId[] optionalDependentPluginIds = pluginNode.getOptionalDependentPluginIds();
       final List<PluginNode> depends = new ArrayList<>();
@@ -141,7 +141,7 @@ public class PluginInstaller {
         PluginId depPluginId = pluginNode.getDepends().get(i);
         if (PluginManager.isPluginInstalled(depPluginId) || PluginManagerCore.isModuleDependency(depPluginId) ||
             InstalledPluginsState.getInstance().wasInstalled(depPluginId) ||
-            (pluginIds != null && pluginIds.contains(depPluginId))) {
+            pluginIds != null && pluginIds.contains(depPluginId)) {
           // ignore installed or installing plugins
           continue;
         }
@@ -150,7 +150,8 @@ public class PluginInstaller {
         PluginNode depPlugin;
         if (depPluginDescriptor instanceof PluginNode) {
           depPlugin = (PluginNode) depPluginDescriptor;
-        } else {
+        }
+        else {
           depPlugin = new PluginNode(depPluginId, depPluginId.getIdString(), "-1");
         }
 
@@ -164,7 +165,7 @@ public class PluginInstaller {
         }
       }
 
-      if (depends.size() > 0) { // has something to install prior installing the plugin
+      if (!depends.isEmpty()) { // has something to install prior installing the plugin
         final boolean[] proceed = new boolean[1];
         try {
           ApplicationManager.getApplication().invokeAndWait(() -> {
@@ -182,7 +183,7 @@ public class PluginInstaller {
         }
       }
 
-      if (optionalDeps.size() > 0) {
+      if (!optionalDeps.isEmpty()) {
         final boolean[] proceed = new boolean[1];
         try {
           ApplicationManager.getApplication().invokeAndWait(() -> {
diff --git a/platform/platform-impl/src/com/intellij/ide/plugins/PluginNode.java b/platform/platform-impl/src/com/intellij/ide/plugins/PluginNode.java
index 801ff368537b..2fe7f324c93f 100644
--- a/platform/platform-impl/src/com/intellij/ide/plugins/PluginNode.java
+++ b/platform/platform-impl/src/com/intellij/ide/plugins/PluginNode.java
@@ -56,17 +56,17 @@ public class PluginNode implements IdeaPluginDescriptor {
 
   public PluginNode() { }
 
-  public PluginNode(PluginId id) {
+  public PluginNode(@NotNull PluginId id) {
     this.id = id;
   }
 
-  public PluginNode(PluginId id, String name, String size) {
+  public PluginNode(@NotNull PluginId id, String name, String size) {
     this.id = id;
     this.name = name;
     this.size = size;
   }
 
-  public void setCategory(String category) {
+  public void setCategory(@NotNull String category) {
     this.category = category;
   }
 
@@ -75,14 +75,14 @@ public class PluginNode implements IdeaPluginDescriptor {
     return name;
   }
 
-  public void setName(String name) {
+  public void setName(@NotNull String name) {
     if (id == null) {
       id = PluginId.getId(name);
     }
     this.name = name;
   }
 
-  public void setId(String id) {
+  public void setId(@NotNull String id) {
     this.id = PluginId.getId(id);
   }
 
@@ -140,7 +140,7 @@ public class PluginNode implements IdeaPluginDescriptor {
     return vendor;
   }
 
-  public void setVendor(String vendor) {
+  public void setVendor(@NotNull String vendor) {
     this.vendor = vendor;
   }
 
@@ -158,7 +158,7 @@ public class PluginNode implements IdeaPluginDescriptor {
     return changeNotes;
   }
 
-  public void setChangeNotes(String changeNotes) {
+  public void setChangeNotes(@NotNull String changeNotes) {
     this.changeNotes = changeNotes;
   }
 
@@ -263,12 +263,12 @@ public class PluginNode implements IdeaPluginDescriptor {
     return myDependencies;
   }
 
-  public void setDepends(List<PluginId> depends, @Nullable PluginId[] optionalDependencies) {
+  public void setDepends(@NotNull List<? extends PluginId> depends, @Nullable PluginId[] optionalDependencies) {
     myDependencies = new ArrayList<>(depends);
     myOptionalDependencies = optionalDependencies;
   }
 
-  public void addDepends(String id) {
+  public void addDepends(@NotNull String id) {
     (myDependencies != null ? myDependencies : (myDependencies = new ArrayList<>())).add(PluginId.getId(id));
   }
 
@@ -276,11 +276,11 @@ public class PluginNode implements IdeaPluginDescriptor {
     return myTags;
   }
 
-  public void setTags(List<String> tags) {
+  public void setTags(@NotNull List<String> tags) {
     myTags = new ArrayList<>(tags);
   }
 
-  void addTags(String tag) {
+  void addTags(@NotNull String tag) {
     (myTags != null ? myTags : (myTags = new ArrayList<>())).add(tag);
   }
 
diff --git a/platform/platform-impl/src/com/intellij/ide/plugins/RepositoryContentHandler.java b/platform/platform-impl/src/com/intellij/ide/plugins/RepositoryContentHandler.java
index f8b53a1cf27f..532e25eb2613 100644
--- a/platform/platform-impl/src/com/intellij/ide/plugins/RepositoryContentHandler.java
+++ b/platform/platform-impl/src/com/intellij/ide/plugins/RepositoryContentHandler.java
@@ -151,6 +151,7 @@ class RepositoryContentHandler extends DefaultHandler {
     currentValue.append(ch, start, length);
   }
 
+  @NotNull
   private String buildCategoryName() {
     if (categoryName == null) {
       StringBuilder builder = new StringBuilder();