[IndentDetector] CONTINUATION_WITHOUT_FIRST indent of the outermost block is treated as CONTINUATION, while the rest are treated as NONE

Every null indent retrieved from Block build by FormattingModelBuilder.buildBlocks is converted to CONTINUATION_WITHOUT_FIRST.  Nested blocks starts the same offset and are retrieved as first block of it's parent that's why CONTINUATION_WITHOUT_FIRST works in such a case as NONE (because they are literally first blocks, see CWF javadoc)

java/java-tests/testData/psi/autodetect/XmlContinuationWithoutFirst.xml

@@ -0,0 +1,32 @@
+<Block start="0" end="50">
+  <Indent type="NONE"/>
+  <Block start="0" end="13">
+    <Indent type="NONE"/>
+  </Block>
+  <Block start="18" end="35">
+    <Indent type="NONE"/>
+    <Block start="18" end="25">
+      <Indent type="NORMAL"/>
+      <Block start="18" end="25">
+        <Indent type="NONE"/>
+        <Block start="18" end="19"/>
+        <Block start="20" end="25">
+          <Indent type="NONE"/>
+        </Block>
+      </Block>
+    </Block>
+    <Block start="30" end="35">
+      <Indent type="NORMAL"/>
+      <Block start="30" end="35">
+        <Indent type="NONE"/>
+        <Block start="30" end="31"/>
+        <Block start="32" end="35">
+          <Indent type="NONE"/>
+        </Block>
+      </Block>
+    </Block>
+  </Block>
+  <Block start="36" end="50">
+    <Indent type="NONE"/>
+  </Block>
+</Block>

java/java-tests/testSrc/com/intellij/psi/codeStyle/autodetect/FormatterBasedLineInfoBuilderTest.java

@@ -40,17 +40,32 @@ public class FormatterBasedLineInfoBuilderTest extends LightPlatformCodeInsightT
     String text = "/**\n" +
                   " *\n" +
                   " */";
-    
+
+    List<LineIndentInfo> infos = getLineInfos(text);
+    assertLinesWithNormalIndent(infos, 0);
+  }
+  
+  public void testXmlContinuationWithoutFirst() throws IOException, JDOMException {
+    String text = "<idea-plugin>\n" +
+                  "    <name/>\n" +
+                  "    <id/>\n" +
+                  "</idea-plugin>";
+
+    List<LineIndentInfo> infos = getLineInfos(text);
+    assertLinesWithNormalIndent(infos, 4);
+  }
+
+  private static void assertLinesWithNormalIndent(List<LineIndentInfo> infos, int expected) {
+    long linesWithNormalIndent = infos.stream().filter(LineIndentInfo::isLineWithNormalIndent).count();
+    assertEquals(expected, linesWithNormalIndent);
+  }
+
+  private List<LineIndentInfo> getLineInfos(String text) throws IOException, JDOMException {
     String file = getTestName(false) + ".xml";
-    
     TestFormattingModel model = new TestFormattingModel(text);
     Document document = model.getDocument();
     TestBlock block = new FormattingModelXmlReader(model).readTestBlock(getTestDataPath(), file);
-    
     FormatterBasedLineIndentInfoBuilder builder = new FormatterBasedLineIndentInfoBuilder(document, block);
-    
-    List<LineIndentInfo> infos = builder.build();
-    long linesWithNormalIndents = infos.stream().filter(LineIndentInfo::isLineWithNormalIndent).count();
-    assertEquals(0, linesWithNormalIndents);
+    return builder.build();
   }
 }

platform/lang-impl/src/com/intellij/psi/codeStyle/autodetect/FormatterBasedLineIndentInfoBuilder.java

@@ -19,6 +19,7 @@ import com.intellij.formatting.ASTBlock;
 import com.intellij.formatting.Block;
 import com.intellij.formatting.Indent;
 import com.intellij.openapi.editor.Document;
+import com.intellij.openapi.util.Condition;
 import com.intellij.openapi.util.TextRange;
 import com.intellij.psi.PsiComment;
 import com.intellij.psi.formatter.common.AbstractBlock;
@@ -58,7 +59,7 @@ public class FormatterBasedLineIndentInfoBuilder {
           return LineIndentInfo.LINE_WITH_TABS;
         }
         
-        if (hasTotallyNormalOrNoneIndent(newLineBlock)) {
+        if (hasNormalIndent(newLineBlock)) {
           return LineIndentInfo.newNormalIndent(blockStartOffset - lineStartOffset);
         }
         else {
@@ -68,22 +69,50 @@ public class FormatterBasedLineIndentInfoBuilder {
     });
   }
   
-  private static boolean hasTotallyNormalOrNoneIndent(Block block) {
+  private static boolean hasNormalIndent(Block block) {
     final TextRange range = block.getTextRange();
     final int startOffset = range.getStartOffset();
-    
-    boolean startOffsetAlreadyHasNormalIndent = false;
-    
-    while (block != null && range.getStartOffset() == startOffset) {
-      Indent.Type type = block.getIndent() != null ? block.getIndent().getType() : null;
-      
-      if (type == Indent.Type.NONE || type == Indent.Type.NORMAL && !startOffsetAlreadyHasNormalIndent) {
-        startOffsetAlreadyHasNormalIndent = true;
+  
+    List<Indent.Type> allIndents = getIndentOnStartOffset(block, range, startOffset);
+
+    if (hasOnlyNormalOrNoneIndents(allIndents)) {
+      int normalIndents = ContainerUtil.filter(allIndents, new Condition<Indent.Type>() {
+      @Override
+      public boolean value(Indent.Type type) {
+        return type == Indent.Type.NORMAL;
       }
-      else {
+    }).size();
+      return normalIndents < 2;
+    }
+    
+    return false;
+  }
+
+  private static boolean hasOnlyNormalOrNoneIndents(List<Indent.Type> indents) {
+    Indent.Type outerMostIndent = indents.get(0);
+    if (outerMostIndent != Indent.Type.NONE && outerMostIndent != Indent.Type.NORMAL) {
+      return false;
+    }
+
+    List<Indent.Type> innerIndents = indents.subList(1, indents.size());
+    for (Indent.Type indent : innerIndents) {
+      if (indent != Indent.Type.NONE && indent != Indent.Type.NORMAL 
+          && indent != Indent.Type.CONTINUATION_WITHOUT_FIRST) {
+        //continuation without first here because it is CONTINUATION only if it's owner is not the first child
         return false;
       }
+    }
 
+    return true;
+  }
+
+  private static List<Indent.Type> getIndentOnStartOffset(Block block, TextRange range, int startOffset) {
+    List<Indent.Type> indentsOnStartOffset = new ArrayList<Indent.Type>();
+    
+    while (block != null && range.getStartOffset() == startOffset) {
+      Indent.Type type = block.getIndent() != null ? block.getIndent().getType() : Indent.Type.CONTINUATION_WITHOUT_FIRST;
+      indentsOnStartOffset.add(type);
+      
       if (block instanceof AbstractBlock) {
         ((AbstractBlock)block).setBuildIndentsOnly(true);
       }
@@ -91,7 +120,7 @@ public class FormatterBasedLineIndentInfoBuilder {
       block = subBlocks.isEmpty() ? null : subBlocks.get(0);
     }
     
-    return true;
+    return indentsOnStartOffset;
   }
 
   @NotNull