code: public void checkClass() {
      ClassNode cv = new ClassNode();
      new ClassReader(data).accept(new CheckClassAdapter(cv, true /* check data flow */), 0);
      // double check our fields while we are here.
      checkState(type.internalName().equals(cv.name));
      checkState(numberOfFields == cv.fields.size());
    }
docs: Runs the {@link CheckClassAdapter} on this class in basic analysis mode.
  
  <p>Basic anaylsis mode can flag verification errors that don't depend on knowing complete type
  information for the classes and methods being called. This is useful for flagging simple
  generation mistakes (e.g. stack underflows, method return type mismatches, accessing invalid
  locals). Additionally, the error messages are more useful than what the java verifier normally
  presents.