Fixes #1849. Changed DefaultNamingService.xtend to use a JDK 9 compat… (#1850)

* Fixes #1849. Changed DefaultNamingService.xtend to use a JDK 9 compatible regex for string replacement for identifier.

* fixes invalid code generation with JDK 9

plugins/org.yakindu.sct.model.sexec/src/org/yakindu/sct/model/sexec/naming/DefaultNamingService.xtend

@@ -286,7 +286,7 @@ class DefaultNamingService implements INamingService {
 	}
 
 	override asIdentifier(String string) {
-		string.replaceAll('[^a-z&&[^A-Z&&[^0-9]]]', separator.toString)
+		string.replaceAll('[[^a-z]&&[^A-Z]&&[^0-9]]', separator.toString)
 	}
 
 	override asEscapedIdentifier(String string) {