// from GSON project
static final class ParameterizedTypeImpl implements ParameterizedType, Serializable {
  private final Type ownerType;
  private final Type rawType;
  private final Type[] typeArguments;

  public ParameterizedTypeImpl(Type ownerType, Type rawType, Type... typeArguments) {
    // require an owner type if the raw type needs it
    if (rawType instanceof Class<?>) {
      Class<?> rawTypeAsClass = (Class<?>) rawType;
      boolean isStaticOrTopLevelClass = Modifier.isStatic(rawTypeAsClass.getModifiers())
          || rawTypeAsClass.getEnclosingClass() == null;
      checkArgument(ownerType != null || isStaticOrTopLevelClass);
    }

    this.ownerType = ownerType == null ? null : canonicalize(ownerType);
    this.rawType = canonicalize(rawType);
    this.typeArguments = typeArguments.clone();
    for (int t = 0, length = this.typeArguments.length; t < length; t++) {
      checkNotNull(this.typeArguments[t]);
      checkNotPrimitive(this.typeArguments[t]);
      this.typeArguments[t] = canonicalize(this.typeArguments[t]);
    }
  }

  public Type[] getActualTypeArguments() {
    return typeArguments.clone();
  }

  public Type getRawType() {
    return rawType;
  }

  public Type getOwnerType() {
    return ownerType;
  }

  @Override public boolean equals(Object other) {
    return other instanceof ParameterizedType
        && $Gson$Types.equals(this, (ParameterizedType) other);
  }

  @Override public int hashCode() {
    return Arrays.hashCode(typeArguments)
        ^ rawType.hashCode()
        ^ hashCodeOrZero(ownerType);
  }

  @Override public String toString() {
    int length = typeArguments.length;
    if (length == 0) {
      return typeToString(rawType);
    }

    StringBuilder stringBuilder = new StringBuilder(30 * (length + 1));
    stringBuilder.append(typeToString(rawType)).append("<").append(typeToString(typeArguments[0]));
    for (int i = 1; i < length; i++) {
      stringBuilder.append(", ").append(typeToString(typeArguments[i]));
    }
    return stringBuilder.append(">").toString();
  }

  private static final long serialVersionUID = 0;
}