code: private void checkConstantPoolIndex(int index) throws InvalidClassFileFormatException {
          if (index < 0 || index >= constantPool.length || constantPool[index] == null) {
              throw new InvalidClassFileFormatException(expectedClassDescriptor, codeBaseEntry);
          }
      }
docs: Check that a constant pool index is valid.
  
  @param index
  the index to check
  @throws InvalidClassFileFormatException
  if the index is not valid