public static Type internReturnType(String descriptor) {
    try {
      if (descriptor.equals("V")) {
        // This is the one special case where void may be returned.
        return VOID;
      }
    } catch (NullPointerException ex) {
      // Elucidate the exception.
      throw new NullPointerException("descriptor == null");
    }

    return intern(descriptor);
  }
Returns the unique instance corresponding to the type with the given descriptor, allowing
{@code "V"} to return the type for {@code void}. Other than that one caveat, this method is
identical to {@link #intern}.

@param descriptor {@code non-null;} the descriptor
@return {@code non-null;} the corresponding instance
@throws IllegalArgumentException thrown if the descriptor has invalid syntax
android/android_framework/dex-maker/src/main/java/com/android/dx/rop/type/Type.java