Fixed the ambiguous identical class names.

Change-Id: I0a809cf0c2bbd4a42fcc73374bbfc34ce561bd8c
diff --git a/src/main/antlr/annis/AqlParser.g4 b/src/main/antlr/annis/AqlParser.g4
index 319ad1b..ea719d1 100644
--- a/src/main/antlr/annis/AqlParser.g4
+++ b/src/main/antlr/annis/AqlParser.g4
@@ -99,11 +99,11 @@
 ;
 
 commonparent
-: COMMON_PARENT (label)? # CommonParent
+: COMMON_PARENT (label)? # CommonParentLabel
 ;
 
 commonancestor
-: COMMON_PARENT (label)? STAR # CommonAncestor
+: COMMON_PARENT (label)? STAR # CommonAncestorLabel
 ;
 
 identity