Initial code

.editorconfig

+# Drupal editor configuration normalization
+# @see http://editorconfig.org/
+
+# This is the top-most .editorconfig file; do not search in parent directories.
+root = true
+
+# All files.
+[*]
+end_of_line = LF
+indent_style = space
+indent_size = 2
+charset = utf-8
+trim_trailing_whitespace = true
+insert_final_newline = true
+
+[{composer.json,composer.lock}]
+indent_size = 4

.gitignore

+vendor
+composer.lock

.gitlab-ci.yml

+Deploy:
+  script:
+    - curl -XPOST -H'content-type:application/json' "https://packagist.org/api/update-package?username=${PACKAGIST_USERNAME}&apiToken=${PACKAGIST_API_TOKEN}" -d'{"repository":{"url":"'${CI_PROJECT_URL}'"}}'

README.md

+# composer.json Tools
+

Utils.php

+<?php
+
+namespace LakeDrops\Component\Composer;
+
+use Composer\Composer;
+use Composer\Json\JsonFile;
+
+/**
+ * Manages composer.json files.
+ */
+final class Utils {
+
+  /**
+   * The composer object running this session.
+   *
+   * @var \Composer\Composer
+   */
+  protected $composer;
+
+  /**
+   * Content of the project's composer.json file.
+   *
+   * @var array
+   */
+  protected $content;
+
+  /**
+   * The path of the root project's directory.
+   *
+   * @var string
+   */
+  protected $sourcePath;
+
+  /**
+   * The full filename of the composer.json file.
+   *
+   * @var string
+   */
+  protected $composerJsonPath;
+
+  /**
+   * Utils constructor.
+   *
+   * @param \Composer\Composer $composer
+   *   The composer object running this session.
+   */
+  public function __construct(Composer $composer) {
+    $this->composer = $composer;
+    $this->sourcePath = $composer->getPackage()->getTargetDir();
+    $this->composerJsonPath = $this->sourcePath . '/composer.json';
+    $this->read();
+  }
+
+  /**
+   * Read the current content of the project's composer.json file.
+   *
+   * @return $this
+   */
+  public function read() {
+    $this->content = [];
+    if (file_exists($this->composerJsonPath)) {
+      $jsonFile = new JsonFile($this->composerJsonPath);
+      $this->content = $jsonFile->read();
+    }
+    return $this;
+  }
+
+  /**
+   * Write the config to composer.json file.
+   *
+   * @return $this
+   */
+  public function write() {
+    $jsonFile = new JsonFile($this->composerJsonPath);
+    if (file_exists($this->composerJsonPath)) {
+      $content = $jsonFile->read();
+      if (md5(json_encode($content)) == md5(json_encode($this->content))) {
+        // Nothing has changed.
+        return $this;
+      }
+    }
+    $jsonFile->write($this->content);
+    return $this;
+  }
+
+  /**
+   * Get settings for [$key].
+   *
+   * @param string $key
+   *   The key for the section.
+   *
+   * @return array|string
+   *   The settings of the key.
+   */
+  public function getSection($key) {
+    return isset($this->content[$key]) ? $this->content[$key] : [];
+  }
+
+  /**
+   * Get settings for [$key1][$key2].
+   *
+   * @param string $key1
+   *   The key for the section.
+   * @param string $key2
+   *   The key for the sub-section.
+   *
+   * @return array|string
+   *   The settings of the key.
+   */
+  public function getSubSection($key1, $key2) {
+    $section = $this->getSection($key1);
+    return isset($section[$key2]) ? $section[$key2] : [];
+  }
+
+  /**
+   * Set settings for [$key].
+   *
+   * @param string $key
+   *   The key for the section.
+   * @param array|string $value
+   *   The value for the section.
+   *
+   * @return $this
+   */
+  public function setSection($key, $value) {
+    $this->content[$key] = $value;
+    return $this;
+  }
+
+  /**
+   * Set settings for [$key1][$key2].
+   *
+   * @param string $key1
+   *   The key for the section.
+   * @param string $key2
+   *   The key for the sub-section.
+   * @param array|string $value
+   *   The value for the sub-section.
+   *
+   * @return $this
+   */
+  public function setSubSection($key1, $key2, $value) {
+    $this->content[$key1][$key2] = $value;
+    return $this;
+  }
+
+}

composer.json

+{
+    "name": "lakedrops/composer-json-tools",
+    "description": "Composer Library to provide tools to work with projects own composer.json file",
+    "type": "library",
+    "keywords": ["Drupal", "Development", "Composer"],
+    "homepage": "https://gitlab.lakedrops.com/lakedrops/composer-json-tools",
+    "license": "GPL-2.0+",
+    "authors": [
+        {
+            "name": "Jürgen Haas",
+            "email": "juergen@paragon-es.de",
+            "homepage": "https://www.paragon-es.de",
+            "role": "Drupal Expert"
+        },
+        {
+            "name": "Richard Papp",
+            "email": "richard.papp@boromino.com",
+            "homepage": "http://www.boromino.com",
+            "role": "Drupal Expert"
+        }
+    ],
+    "support": {
+        "issues": "https://gitlab.lakedrops.com/lakedrops/composer-json-tools/issues",
+        "source": "https://gitlab.lakedrops.com/lakedrops/composer-json-tools/tree/master"
+    },
+    "require": {
+        "php": ">=5.6"
+    },
+    "autoload": {
+        "psr-4": { "LakeDrops\\Component\\Composer\\": "" }
+    },
+    "require-dev": {
+        "composer/composer": "dev-master",
+        "dealerdirect/phpcodesniffer-composer-installer": "^0.4.3",
+        "drupal/coder": "^8.2",
+        "phpunit/phpunit": "^4.4.0"
+    }
+}