remove unused constants

Author: sanchitmalhotra126

org-code-javabuilder/lib/src/main/java/org/code/javabuilder/UserInitiatedExceptionKey.java

@@ -10,11 +10,8 @@ public enum UserInitiatedExceptionKey {
   TWO_MAIN_METHODS,
   // The user's code does not contain a main method.
   NO_MAIN_METHOD,
+  // The user's main method has an invalid signature.
   INVALID_MAIN_METHOD,
-  MAIN_METHOD_NOT_PUBLIC,
-  MAIN_METHOD_NOT_STATIC,
-  MAIN_METHOD_NOT_VOID,
-  MAIN_METHOD_WRONG_ARGUMENTS,
   // The user's code has a compiler error.
   COMPILER_ERROR,
   // The user tried to include a source file that did not end in .java