[ONOS-5058][ONOS-4796][ONOS-4893]compiler annotation implementation + defect fix

Change-Id: Ie317409d9ab1d36e626433558b2d51f26daaac82
diff --git a/plugin/src/main/resources/YangLexer.g4 b/plugin/src/main/resources/YangLexer.g4
index 8abe32f..51a9231 100644
--- a/plugin/src/main/resources/YangLexer.g4
+++ b/plugin/src/main/resources/YangLexer.g4
@@ -133,7 +133,7 @@
     PLUS : '+';
     MINUS: '-';
 
-    STRING : ((~( '\r' | '\n' | '\t' | ' ' | ';' | '{' | '"' | '\'')~( '\r' | '\n' | '\t' | ' ' | ';' | '{' )* ) | SUB_STRING );
+    STRING : ((~( '\r' | '\n' | '\t' | ' ' | ';' | '{' | '"' | '+' | '\'')~( '\r' | '\n' | '\t' | ' ' | ';' | '{' | '+')* ) | SUB_STRING );
 
     //Fragment rules
     fragment SUB_STRING : ('"' (ESC | ~["])*'"') | ('\'' (ESC | ~['])*'\'') ;