Bug 251786 - Make XMLContentDescriber INDETERMINATE on parse errors

Change the XMLContentDescriber so that when the description is
null, it returns as INDETERMINATE instead of VALID, allowing
other describers to potentially extract more details.

Change-Id: I6059ffb6900369fe8bdb10b17eb7bf1efcee64c5
Signed-off-by: Nitin Dahyabhai <thatnitind@gmail.com>
diff --git a/bundles/org.eclipse.core.contenttype/src/org/eclipse/core/runtime/content/XMLContentDescriber.java b/bundles/org.eclipse.core.contenttype/src/org/eclipse/core/runtime/content/XMLContentDescriber.java
index 35ca74e..9fcbc07 100644
--- a/bundles/org.eclipse.core.contenttype/src/org/eclipse/core/runtime/content/XMLContentDescriber.java
+++ b/bundles/org.eclipse.core.contenttype/src/org/eclipse/core/runtime/content/XMLContentDescriber.java
@@ -1,5 +1,5 @@
 /*******************************************************************************
- * Copyright (c) 2004, 2010 IBM Corporation and others.
+ * Copyright (c) 2004, 2020 IBM Corporation and others.
  *
  * This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License 2.0
@@ -122,7 +122,7 @@
 		if (fullXMLDecl == null || !fullXMLDecl.booleanValue())
 			return INDETERMINATE;
 		if (description == null)
-			return VALID;
+			return INDETERMINATE;
 		String charset = (String) properties.get(CHARSET);
 		if (description.isRequested(IContentDescription.CHARSET)) {
 			if (charset != null && !isCharsetValid(charset))