[480502] Fixed NPE in GenCustomPropertyTabImpl.getClassName()

Change-Id: Ide00901f214c41bcc31787cd4599345ad1001f60
diff --git a/plugins/org.eclipse.gmf.codegen/src/org/eclipse/gmf/codegen/gmfgen/impl/GenCustomPropertyTabImpl.java b/plugins/org.eclipse.gmf.codegen/src/org/eclipse/gmf/codegen/gmfgen/impl/GenCustomPropertyTabImpl.java
index 0f02448..d7e633d 100644
--- a/plugins/org.eclipse.gmf.codegen/src/org/eclipse/gmf/codegen/gmfgen/impl/GenCustomPropertyTabImpl.java
+++ b/plugins/org.eclipse.gmf.codegen/src/org/eclipse/gmf/codegen/gmfgen/impl/GenCustomPropertyTabImpl.java
@@ -114,6 +114,11 @@
 
 	public String getClassName() {
 		String rv = getClassNameGen();
+		
+		//Fix for 480502
+		if(getSheet() == null || getSheet().getEditorGen() == null)
+			return rv;
+		
 		if (rv == null || rv.trim().length() == 0) {
 			return ((GenEditorGeneratorImpl) getSheet().getEditorGen()).getDomainModelCapName() + "PropertySection";
 		}