java_class: improve is_two_entries to prevent 'ConstantPoolEntry' object has no attribute 'tag' error in generated Python code

[armijnhemel]

I bumped into an error where when using a Python generated with the .ksy I would get an error: "ConstantPoolEntry' object has no attribute 'tag' for the second entry of entries that take up two entries (long and double).

The generated code looks like this:

@property
 def is_two_entries(self):
        if hasattr(self, '_m_is_two_entries'):
            return self._m_is_two_entries if hasattr(self, '_m_is_two_entries') else None

        self._m_is_two_entries =  ((self.tag == JavaClass.ConstantPoolEntry.TagEnum.long) or (self.tag == JavaClass.ConstantPoolEntry.TagEnum.double)) 
        return self._m_is_two_entries if hasattr(self, '_m_is_two_entries') else None

The problem here is that it tries to find self.tag which doesn't exist for these "second entries":

def _read(self):
    if not (self.is_prev_two_entries):
        self.tag = KaitaiStream.resolve_enum(JavaClass.ConstantPoolEntry.TagEnum, self._io.read_u1())

As you can see self.tag does not exist for these entries.

In the Web IDE this is not a problem.