code: public ClassFile addInnerClass(String innerClassName, String superClassName) {
          ClassFile inner;
          if (innerClassName == null) {
              inner = mParent.addInnerClass(null, null, superClassName);
          } else {
              String fullInnerClassName = mParent.getClassName() + '$' +
                  (++mAnonymousInnerClassCount) + innerClassName;
              inner = mParent.addInnerClass(fullInnerClassName, innerClassName, superClassName);
          }
  
          if (mParent.getMajorVersion() >= 49) {
              inner.addAttribute(new EnclosingMethodAttr
                                 (mCp, mCp.addConstantClass(mParent.getClassName()),
                                  mCp.addConstantNameAndType(mNameConstant, mDescriptorConstant)));
          }
  
          return inner;
      }
docs: Add an inner class to this method.
  
  @param innerClassName Optional short inner class name.
  @param superClassName Full super class name.