don't create empty groovyc.xml

platform/lang-impl/src/com/intellij/psi/impl/source/codeStyle/CodeFormatterFacade.java

@@ -21,8 +21,6 @@ import com.intellij.psi.impl.source.SourceTreeToPsiMap;
 import com.intellij.psi.util.PsiTreeUtil;
 import com.intellij.util.IncorrectOperationException;
 
-import java.io.IOException;
-
 public class CodeFormatterFacade {
   private static final Logger LOG = Logger.getInstance("#com.intellij.psi.impl.source.codeStyle.CodeFormatterFacade");
 
@@ -123,15 +121,10 @@ public class CodeFormatterFacade {
   }
 
   private void printToConsole(final Block rootBlock, final FormattingModel model) {
-    try {
-      String tree = JDOMUtil.writeElement(new FormatInfoPrinter(rootBlock, model.getDocumentModel()).blocksAsTree(), "\n");
-      System.out.println("---TREE---");
-      System.out.println(tree);
-      System.out.println("---/TREE---");
-    }
-    catch (IOException e) {
-      e.printStackTrace();
-    }
+    String tree = JDOMUtil.writeElement(new FormatInfoPrinter(rootBlock, model.getDocumentModel()).blocksAsTree(), "\n");
+    System.out.println("---TREE---");
+    System.out.println(tree);
+    System.out.println("---/TREE---");
   }
 
   public void processTextWithoutHeadWhitespace(final PsiFile file, final int startOffset, final int endOffset) {

platform/platform-impl/src/com/intellij/openapi/components/impl/stores/DefaultStateSerializer.java

@@ -15,7 +15,6 @@ import org.jdom.Element;
 import org.jetbrains.annotations.Nullable;
 
 import java.lang.annotation.Annotation;
-import java.io.IOException;
 
 
 @SuppressWarnings({"deprecation"})
@@ -80,13 +79,8 @@ class DefaultStateSerializer {
     }
     else if (JDOMExternalizable.class.isAssignableFrom(stateClass)) {
       if (mergeInto != null) {
-        try {
-          String elementText = JDOMUtil.writeElement(stateElement, "\n");
-          LOG.error("State is " + stateClass.getName() + ", merge into is " + mergeInto.toString() + ", state element text is " + elementText);
-        }
-        catch (IOException e) {
-          LOG.error(e);
-        }
+        String elementText = JDOMUtil.writeElement(stateElement, "\n");
+        LOG.error("State is " + stateClass.getName() + ", merge into is " + mergeInto.toString() + ", state element text is " + elementText);
       }
       try {
         final T t = stateClass.newInstance();

platform/platform-impl/src/com/intellij/openapi/components/impl/stores/StorageUtil.java

@@ -151,12 +151,7 @@ public class StorageUtil {
   }
 
   static String printElement(Element element) throws StateStorage.StateStorageException {
-    try {
-      return JDOMUtil.writeElement(element, SystemProperties.getLineSeparator());
-    }
-    catch (IOException e) {
-      throw new StateStorage.StateStorageException(e);
-    }
+    return JDOMUtil.writeElement(element, SystemProperties.getLineSeparator());
   }
 
   static void save(IFile file, Element element) throws StateStorage.StateStorageException {

platform/util/src/com/intellij/openapi/util/JDOMUtil.java

@@ -403,10 +403,15 @@ public class JDOMUtil {
   }
 
   @NotNull
-  public static String writeElement(Element element, String lineSeparator) throws IOException {
-    final StringWriter writer = new StringWriter();
-    writeElement(element, writer, lineSeparator);
-    return writer.toString();
+  public static String writeElement(Element element, String lineSeparator) {
+    try {
+      final StringWriter writer = new StringWriter();
+      writeElement(element, writer, lineSeparator);
+      return writer.toString();
+    }
+    catch (IOException ignored) {
+      throw new RuntimeException(ignored);
+    }
   }
 
   public static void writeDocument(Document document, Writer writer, String lineSeparator) throws IOException {

platform/util/src/com/intellij/util/xmlb/SkipDefaultValuesSerializationFilters.java

@@ -17,6 +17,8 @@
 package com.intellij.util.xmlb;
 
 import com.intellij.openapi.util.Comparing;
+import com.intellij.openapi.util.JDOMUtil;
+import org.jdom.Element;
 
 import java.util.HashMap;
 import java.util.Map;
@@ -27,7 +29,13 @@ public class SkipDefaultValuesSerializationFilters implements SerializationFilte
   public boolean accepts(final Accessor accessor, final Object bean) {
     Object defaultBean = getDefaultBean(bean);
 
-    return !Comparing.equal(accessor.read(bean), accessor.read(defaultBean));
+    final Object defValue = accessor.read(defaultBean);
+    final Object beanValue = accessor.read(bean);
+    if (defValue instanceof Element && beanValue instanceof Element) {
+      return !JDOMUtil.writeElement((Element)defValue, "\n").equals(JDOMUtil.writeElement((Element)beanValue, "\n"));
+    }
+
+    return !Comparing.equal(beanValue, defValue);
   }
 
   private Object getDefaultBean(final Object bean) {