[eclipse/xtext-core#1909] solve circular proxy problems

Signed-off-by: Christian Dietrich <christian.dietrich@itemis.de>

org.eclipse.xtext.xbase/src/org/eclipse/xtext/xbase/conversion/XbaseQualifiedNameValueConverter.java

@@ -56,7 +56,7 @@ public String toValue(String string, INode node) throws ValueConverterException
 				if(getWildcardLiteral().equals(segment)) {
 					buffer.append(getWildcardLiteral());
 				} else {
-					buffer.append((String) valueConverterService.toValue(segment, getDelegateRuleName(), null));
+					buffer.append((String) valueConverterService.get().toValue(segment, getDelegateRuleName(), null));
 				}
 			}
 		}