feat(maven): validate the project with `.maven:validate`

.maven:validate
===============

Validate the project is correct and all necessary information is
available.

USAGE
=====

include:
  - project: EOLE/Infra/ci-tools
    ref: stable
    file: /templates/Maven.yaml

stages:
  - lint

maven validate: {extends: '.maven:validate'}

templates/Maven.yaml

+# -*- mode: yaml; coding: utf-8 -*-
+# vim: ft=yaml
+#
+# Hidden template jobs to be used in `.gitlab-ci.yml`
+#
+# - `.maven:validate`: validate the project is correct and all
+#   necessary information is available
+#
+# - `.maven:base`: base template job used to factorize variables
+#   declaration
+#
+---
+#
+# .maven:validate
+# ===============
+#
+# Validate the project is correct and all necessary information is
+# available.
+#
+# USAGE
+# =====
+#
+# include:
+#   - project: EOLE/Infra/ci-tools
+#     ref: stable
+#     file: /templates/Maven.yaml
+#
+# stages:
+#   - lint
+#
+# maven validate: {extends: '.maven:validate'}
+#
+# REQUIREMENTS
+# ============
+#
+# - a `lint` stage must be present in your pipeline or it must be
+#   overriden by the extending job to feet your need.
+#
+# - the `.on-branch` rules templates or it must be overriden by
+#   the extending job to feet your need
+#
+# OPTIONAL VARIABLES
+# ==================
+#
+# - `SRC_DIR`: directory of the java sources containing the `pom.xml`,
+#   default to `.`
+#
+# - `MAVEN_IMAGE`: name of the `maven` docker image to use
+#
+# - `MAVEN_OPTS`: default to "-Dhttps.protocols=TLSv1.2 -Dmaven.repo.local=$CI_PROJECT_DIR/.m2/repository -Dorg.slf4j.simpleLogger.log.org.apache.maven.cli.transfer.Slf4jMavenTransferListener=WARN -Dorg.slf4j.simpleLogger.showDateTime=true -Djava.awt.headless=true"
+#
+# - `MAVEN_CLI_OPTS`: default to "--batch-mode --errors --fail-at-end --show-version -DinstallAtEnd=true -DdeployAtEnd=true"
+#
+# - `MAVEN_CLI_ARGS`: optional arguments to pass to `maven validate`
+#   command, empty by default
+#
+# USED CI VARIABLES
+# =================
+#
+.maven:validate:
+  stage: lint
+  extends: .maven:base
+  cache:
+    # This job update dependencies
+    policy: pull-push
+  script:
+    - echo -e "\e[0Ksection_start:$(date +%s):maven-validate\r\e[0KExecute 'mvn validate -f ${SRC_DIR} ${MAVEN_CLI_OPTS} ${MAVEN_CLI_ARGS}'"
+    - mvn validate -f "${SRC_DIR}" ${MAVEN_CLI_OPTS} ${MAVEN_CLI_ARGS}
+    - echo -e "\e[0Ksection_end:$(date +%s):maven-validate\r\e[0K"
+
+
+.maven:base:
+  image: ${MAVEN_IMAGE}
+  extends: .on-branch
+  variables:
+    MAVEN_IMAGE: hub.eole.education/proxyhub/library/maven:3.8.6-openjdk-8-slim
+    MAVEN_OPTS: "-Dhttps.protocols=TLSv1.2 -Dmaven.repo.local=$CI_PROJECT_DIR/.m2/repository -Dorg.slf4j.simpleLogger.log.org.apache.maven.cli.transfer.Slf4jMavenTransferListener=WARN -Dorg.slf4j.simpleLogger.showDateTime=true -Djava.awt.headless=true"
+    MAVEN_CLI_OPTS: "--batch-mode --errors --fail-at-end --show-version -DinstallAtEnd=true -DdeployAtEnd=true"
+    MAVEN_CLI_ARGS: ""
+  cache:
+    key:
+      files:
+        - pom.xml
+    paths:
+      - .m2/repository
+    # Validate will push the cache
+    policy: pull
+...