added colouring for variables inside urls

Author: JessicaJHee

language-support/properties-support/java-properties.tmLanguage.json

@@ -88,7 +88,7 @@
     },
     "expression":{
       "comment": "Matching for expression. Ex : ${expression:value} ${my.prop${compose}} ${my.prop}${my.prop}",
-      "begin": "(?<!\\/)(\\$\\{)",
+      "begin": "(\\$\\{)",
       "beginCaptures": {
         "1": {
           "name": "support.constant.handlebars.java-properties"