fix for GRAILS-6970 "Cannot use 'import' statement in Grails Config"

scripts/Upgrade.groovy

@@ -149,18 +149,15 @@ move it to the new location of '${basedir}/test/integration'. Please move the di
         // add reasonable defaults for them
         def configFile = new File(baseFile, '/grails-app/conf/Config.groovy')
         if (configFile.exists()) {
-            def configSlurper = new ConfigSlurper()
-            def configObject = configSlurper.parse(configFile.toURI().toURL())
-            def defaultCodec = configObject.grails.views.default.codec
-            def gspEncoding = configObject.grails.views.gsp.encoding
-
-            if (!defaultCodec || !gspEncoding) {
-                configFile.withWriterAppend {
-                    it.writeLine '\n// The following properties have been added by the Upgrade process...'
-                    if (!defaultCodec) it.writeLine 'grails.views.default.codec="none" // none, html, base64'
-                    if (!gspEncoding) it.writeLine 'grails.views.gsp.encoding="UTF-8"'
-                }
-            }
+			def configText = configFile.text			
+			configFile.withWriterAppend {
+				if(!configText.contains("grails.views.default.codec") ) {				               
+                    it.writeLine 'grails.views.default.codec="none" // none, html, base64'
+	            }
+				if(!configText.contains("grails.views.gsp.encoding") ) {
+                    it.writeLine 'grails.views.gsp.encoding="UTF-8"'				
+				}
+			}
         }
 
         if (new File("${basedir}/spring").exists()) {