public String getClassName() {
    if (className == null) {
      if (!isReference()) {
        throw new IllegalArgumentException("not an object type: " + descriptor);
      }

      if (descriptor.charAt(0) == '[') {
        className = descriptor;
      } else {
        className = descriptor.substring(1, descriptor.length() - 1);
      }
    }

    return className;
  }
Gets the name of the class this type corresponds to, in internal form. This method is only
valid if this instance is for a normal reference type (that is, a reference type and
additionally not a return address).

@return {@code non-null;} the internal-form class name
android/android_framework/dex-maker/src/main/java/com/android/dx/rop/type/Type.java