Fix the validation issue for main class name (#238)

Signed-off-by: Jinbo Wang <[email protected]>

Author: testforstephen

com.microsoft.java.debug.plugin/src/main/java/com/microsoft/java/debug/plugin/internal/ResolveMainClassHandler.java

@@ -44,7 +44,8 @@
 
 public class ResolveMainClassHandler {
     private static final Logger logger = Logger.getLogger(Configuration.LOGGER_NAME);
-    private static final String CLASSNAME_REGX = "([$\\w]+\\.)*[$\\w]+";
+    // Java command line supports two kinds of main class format: <mainclass> and <module>[/<mainclass>]
+    private static final String CLASSNAME_REGX = "([$\\w]+\\.)*[$\\w]+(/([$\\w]+\\.)*[$\\w]+)?";
 
     /**
      * resolve main class and project name.