When generating java code, enum values starting with digits will be replaced with VALUE_x

[TheMinefighter]

Any enum that contains at least one value which start with e.g. a digit will have all of it's values renamed to VALUE_x in java code generation. That should not happen. Instead an underscore should be added to create a valid java identifier, as it is done at other places in the java code generation too: a package called 12 will be called _12 in generated java code. That should also apply to enum values.