From f19d76fac21f3a0b3d51cc7b7e73451b732a9096 Mon Sep 17 00:00:00 2001
From: Ralf Ueberfuhr <40685729+ueberfuhr@users.noreply.github.com>
Date: Wed, 1 Sep 2021 04:22:43 +0200
Subject: [PATCH] BAEL-5083: add Maven parent POM resolution samples (#11182)

Co-authored-by: Ralf Ueberfuhr <ralf.ueberfuhr@ars.de>
---
 .../maven-parent-pom-resolution/README.md     |  3 ++
 .../maven-parent-pom-resolution/pom.xml       | 28 +++++++++++++++++++
 .../project-a/pom.xml                         | 20 +++++++++++++
 .../project-a/project-b/pom.xml               | 15 ++++++++++
 .../project-a/project-c/pom.xml               | 20 +++++++++++++
 .../project-a/project-c/project-d/pom.xml     | 17 +++++++++++
 maven-modules/pom.xml                         |  1 +
 7 files changed, 104 insertions(+)
 create mode 100644 maven-modules/maven-parent-pom-resolution/README.md
 create mode 100644 maven-modules/maven-parent-pom-resolution/pom.xml
 create mode 100644 maven-modules/maven-parent-pom-resolution/project-a/pom.xml
 create mode 100644 maven-modules/maven-parent-pom-resolution/project-a/project-b/pom.xml
 create mode 100644 maven-modules/maven-parent-pom-resolution/project-a/project-c/pom.xml
 create mode 100644 maven-modules/maven-parent-pom-resolution/project-a/project-c/project-d/pom.xml

diff --git a/maven-modules/maven-parent-pom-resolution/README.md b/maven-modules/maven-parent-pom-resolution/README.md
new file mode 100644
index 0000000000..6f72b5e70b
--- /dev/null
+++ b/maven-modules/maven-parent-pom-resolution/README.md
@@ -0,0 +1,3 @@
+### Relevant Articles:
+
+- [Understanding the "relativePath" Tag - Maven Parent POM Resolution At A Glance](https://www.baeldung.com/maven-relativepath)
diff --git a/maven-modules/maven-parent-pom-resolution/pom.xml b/maven-modules/maven-parent-pom-resolution/pom.xml
new file mode 100644
index 0000000000..62e3946723
--- /dev/null
+++ b/maven-modules/maven-parent-pom-resolution/pom.xml
@@ -0,0 +1,28 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <groupId>com.baeldung</groupId>
+    <artifactId>maven-parent-pom-resolution</artifactId>
+    <version>1.0-SNAPSHOT</version>
+    <packaging>pom</packaging>
+
+    <modules>
+        <module>project-a</module>
+    </modules>
+
+    <!-- to detect the POM hierarchy, just type "mvn dependency:display-ancestors" -->
+    <build>
+        <pluginManagement>
+            <plugins>
+                <plugin>
+                    <groupId>org.apache.maven.plugins</groupId>
+                    <artifactId>maven-dependency-plugin</artifactId>
+                    <version>3.2.0</version>
+                </plugin>
+            </plugins>
+        </pluginManagement>
+    </build>
+
+</project>
diff --git a/maven-modules/maven-parent-pom-resolution/project-a/pom.xml b/maven-modules/maven-parent-pom-resolution/project-a/pom.xml
new file mode 100644
index 0000000000..2d53a36d84
--- /dev/null
+++ b/maven-modules/maven-parent-pom-resolution/project-a/pom.xml
@@ -0,0 +1,20 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <artifactId>project-a</artifactId>
+    <parent>
+        <groupId>com.baeldung</groupId>
+        <artifactId>maven-parent-pom-resolution</artifactId>
+        <version>1.0-SNAPSHOT</version>
+        <!-- The parent pom is resolved to ../pom.xml -->
+    </parent>
+    <packaging>pom</packaging>
+
+    <modules>
+        <module>project-b</module>
+        <module>project-c</module>
+    </modules>
+
+</project>
diff --git a/maven-modules/maven-parent-pom-resolution/project-a/project-b/pom.xml b/maven-modules/maven-parent-pom-resolution/project-a/project-b/pom.xml
new file mode 100644
index 0000000000..e3f5239efe
--- /dev/null
+++ b/maven-modules/maven-parent-pom-resolution/project-a/project-b/pom.xml
@@ -0,0 +1,15 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <artifactId>project-b</artifactId>
+    <parent>
+        <groupId>com.baeldung</groupId>
+        <artifactId>project-a</artifactId>
+        <version>1.0-SNAPSHOT</version>
+        <!-- The parent pom is resolved to project a's pom.xml -->
+    </parent>
+    <packaging>pom</packaging>
+
+</project>
diff --git a/maven-modules/maven-parent-pom-resolution/project-a/project-c/pom.xml b/maven-modules/maven-parent-pom-resolution/project-a/project-c/pom.xml
new file mode 100644
index 0000000000..3c7f70ae20
--- /dev/null
+++ b/maven-modules/maven-parent-pom-resolution/project-a/project-c/pom.xml
@@ -0,0 +1,20 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <artifactId>project-c</artifactId>
+    <parent>
+        <groupId>com.baeldung</groupId>
+        <artifactId>project-b</artifactId>
+        <version>1.0-SNAPSHOT</version>
+        <relativePath>../project-b/pom.xml</relativePath>
+        <!-- The parent pom is resolved to project a's pom.xml -->
+    </parent>
+    <packaging>pom</packaging>
+
+    <modules>
+        <module>project-d</module>
+    </modules>
+
+</project>
diff --git a/maven-modules/maven-parent-pom-resolution/project-a/project-c/project-d/pom.xml b/maven-modules/maven-parent-pom-resolution/project-a/project-c/project-d/pom.xml
new file mode 100644
index 0000000000..973e44eb1f
--- /dev/null
+++ b/maven-modules/maven-parent-pom-resolution/project-a/project-c/project-d/pom.xml
@@ -0,0 +1,17 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <artifactId>project-d</artifactId>
+    <parent>
+        <groupId>com.baeldung</groupId>
+        <artifactId>project-a</artifactId>
+        <version>1.0-SNAPSHOT</version>
+        <!-- removing relativePath won't work even if project-a is the aggregator project -->
+        <!-- it only works in IntelliJ IDEA when project-a is registered as a Maven Project -->
+        <relativePath>../../pom.xml</relativePath>
+    </parent>
+    <packaging>pom</packaging>
+
+</project>
diff --git a/maven-modules/pom.xml b/maven-modules/pom.xml
index a0c45234d2..fe3bbd2653 100644
--- a/maven-modules/pom.xml
+++ b/maven-modules/pom.xml
@@ -36,6 +36,7 @@
         <module>host-maven-repo-example</module>
         <module>plugin-management</module>
         <module>maven-surefire-plugin</module>
+        <module>maven-parent-pom-resolution</module>
     </modules>
 
 </project>