XRENDERING-667: New lines added when parsing and re-rendering groups in xwiki/2.1

xwiki-rendering-integration-tests/src/test/resources/simple/group/group14.test

@@ -0,0 +1,16 @@
+.#-------------------------------------------------------------------
+.inputexpect|xwiki/2.0
+.# Verify that newlines in a group stay unchanged
+.#-------------------------------------------------------------------
+(((
+
+
+)))
+.#-----------------------------------------------------
+.expect|event/1.0
+.#-----------------------------------------------------
+beginDocument
+beginGroup
+onEmptyLines [2]
+endGroup
+endDocument

xwiki-rendering-integration-tests/src/test/resources/simple/id/id.test

@@ -23,7 +23,6 @@ endDocument
 .#-----------------------------------------------------
 (% id="idname1" %)
 (((
-
 )))
 
-before{{id name="idname2"/}}after
+before{{id name="idname2"/}}after

xwiki-rendering-syntaxes/xwiki-rendering-syntax-xwiki20/src/main/java/org/xwiki/rendering/internal/renderer/xwiki20/XWikiSyntaxChainingRenderer.java

@@ -176,7 +176,14 @@ public void endDocument(MetaData metadata)
     @Override
     public void endGroup(Map<String, String> parameters)
     {
-        print("\n");
+        // Flush the internal buffer to ensure we have the correct newline state. Note that the following print()
+        // would flush the buffer, anyway.
+        getXWikiPrinter().flush();
+
+        // Don't print a new line if the last element of the group is a new line.
+        if (!getXWikiPrinter().getEscapeHandler().isOnNewLine()) {
+            print("\n");
+        }
         print(")))");
 
         // Restore previous listeners that were stacked
@@ -958,4 +965,4 @@ protected void popPrinter()
 
         super.popPrinter();
     }
-}
+}