# Istio operator code overview

## Introduction

This document covers primarily the code, with some background on how the design maps to it.
See the
[design doc](https://docs.google.com/document/d/11j9ZtYWNWnxQYnZy8ayZav1FMwTH6F6z6fkDYZ7V298/edit#heading=h.qex63c29z2to)
for a more complete design description. The operator code is divided roughly into five areas:

1. [IstioOperatorSpec API](#istiooperatorspec-api) and related infrastructure, which is expressed as a

 * the execute method.<br>
 * The implementation should have a <code>Mojo</code> annotation with the name of the goal:
 * <pre>
 *   &#64;Mojo( name = "&lt;goal-name&gt;" )
 * </pre>
 * <p>
 * There are also a number of attributes which can be used to control how and when the
 * <code>Mojo</code> is executed:
 * </p>
 * <table border="1">

// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:build ignore

// Compute Fibonacci numbers with two goroutines
// that pass integers back and forth.  No actual
// concurrency, just threads and synchronization
// and foreign code on multiple pthreads.

package main

import (
	big "."
	"runtime"
)

// CHECKSTYLE_OFF: RegexpHeader|LineLength
/**
 * XML reader and writer classes for Maven POM, generated from <code>maven.mdo</code> model.
 * These classes use
 * <a href="https://codehaus-plexus.github.io/plexus-utils/apidocs/org/codehaus/plexus/util/xml/pull/package-summary.html">plexus-utils'
 * XML Pull Parser API</a> for their internal XML handling and

 *
 * @author Ben Yu
 */
@GwtIncompatible
@J2ktIncompatible
@ElementTypesAreNonnullByDefault
abstract class DummyProxy {

  /**
   * Returns a new proxy for {@code interfaceType}. Proxies of the same interface are equal to each
   * other if the {@link DummyProxy} instance that created the proxies are equal.
   */
  final <T> T newProxy(TypeToken<T> interfaceType) {

 *
 * <p>By default, the local repository is located in the {@code .m2/repository}
 * directory within the user's home directory ({@code ~/.m2/repository} on
 * Unix-like systems or {@code C:\Users\YourName\.m2\repository} on Windows).
 * The location of the local repository can be customized in the
 * {@code settings.xml} file.</p>
 *
 * @since 4.0.0
 * @see Repository

     *            <code>null</code>.
     * @param request The model building request that holds further settings, must not be {@code null}.
     * @param problems The container used to collect problems that were encountered, must not be {@code null}.
     */
    void injectLifecycleBindings(Model model, ModelBuildingRequest request, ModelProblemCollector problems);

The return type of `HttpUrl.queryParameterValues()` is `List<String?>`. Lists that may contain null
are uncommon and Kotlin callers may have incorrectly assigned the result to `List<String>`.


Code Cleanup
------------

IntelliJ and Android Studio offer a **Code Cleanup** feature that will automatically update
deprecated APIs with their replacements. Access this feature from the _Search Anywhere_ dialog
(double-press shift) or under the _Analyze_ menu.

Here's where it becomes important to be able to declare <abbr title="greater than"><code>gt</code></abbr> and not just <abbr title="greater than or equal"><code>ge</code></abbr>. As with it you can require, for example, that a value must be greater than `0`, even if it is less than `1`.

So, `0.5` would be a valid value. But `0.0` or `0` would not.

And the same for <abbr title="less than"><code>lt</code></abbr>.

//// tab | Python 3.9+

```Python hl_lines="13"

     *
     * @param child The child model, must not be <code>null</code>.
     * @param parent The parent model, may be <code>null</code>.
     * @param childDirectory The directory defined in child model, may be <code>null</code>.
     * @return The path adjustment, can be empty but never <code>null</code>.
     */
    private String getChildPathAdjustment(Model child, Model parent, String childDirectory) {