Check Maven user properties with highest precedence when fetching a property value (#4345)

* Check Maven user properties with highest precedence when fetching a property value

* Fix formatting

* Update changelog entry

---------

Co-authored-by: ldetmer <[email protected]>
Co-authored-by: Nils Breunese <[email protected]>

Author: 3 people

jib-maven-plugin/CHANGELOG.md

@@ -6,6 +6,7 @@ All notable changes to this project will be documented in this file.
 ### Added
 
 ### Changed
+- Update retrieval of Maven properties to use the following order: user, project, system [#4344](https://github.com/GoogleContainerTools/jib/issues/4344)
 
 ### Fixed
 

jib-maven-plugin/README.md

@@ -27,7 +27,7 @@ For information about the project, see the [Jib project README](../README.md).
   * [Additional Build Artifacts](#additional-build-artifacts)
 * [Multi Module Projects](#multi-module-projects)
 * [Extended Usage](#extended-usage)
-  * [System Properties](#system-properties)
+  * [Configuration Properties](#configuration-properties)
   * [Global Jib Configuration](#global-jib-configuration)
   * [Example](#example)
   * [Adding Arbitrary Files to the Image](#adding-arbitrary-files-to-the-image)
@@ -344,9 +344,9 @@ Property | Type | Default | Description
 `executable` | string | `docker` | Sets the path to the Docker executable that is called to load the image into the Docker daemon. **Please note**: Users are responsible for ensuring that the Docker path passed in is valid and has the right permissions to be executed.
 `environment` | map | *None* | Sets environment variables used by the Docker executable.
 
-#### System Properties
+#### Configuration Properties
 
-Each of these parameters is configurable via commandline using system properties. Jib's system properties follow the same naming convention as the configuration parameters, with each level separated by dots (i.e. `-Djib.parameterName[.nestedParameter.[...]]=value`). Some examples are below:
+Each of these parameters is configurable via commandline using properties. Jib's properties follow the same naming convention as the configuration parameters, with each level separated by dots (i.e. `-Djib.parameterName[.nestedParameter.[...]]=value`). Some examples are below:
 ```shell
 mvn compile jib:build \
     -Djib.to.image=myregistry/myimage:latest \
@@ -359,7 +359,7 @@ mvn compile jib:dockerBuild \
     -Djib.container.args=arg1,arg2,arg3
 ```
 
-The following table contains additional system properties that are not available as build configuration parameters:
+The following table contains additional properties that are not available as build configuration parameters:
 
 Property | Type | Default | Description
 --- | --- | --- | ---

jib-maven-plugin/src/main/java/com/google/cloud/tools/jib/maven/MavenProjectProperties.java

@@ -132,23 +132,27 @@ public static MavenProjectProperties getForProject(
   }
 
   /**
-   * Gets a system property with the given name. First checks for a -D commandline argument, then
-   * checks for a property defined in the POM, then returns null if neither are defined.
+   * Gets a property with the given name. First checks for a Maven user property (-D commandline
+   * argument), then checks for a property defined in the POM, then checks for a Maven system
+   * property, then returns null if none of those are defined.
    *
-   * @param propertyName the name of the system property
+   * @param propertyName the name of the property
    * @param project the Maven project
    * @param session the Maven session
-   * @return the value of the system property, or null if not defined
+   * @return the value of the property, or null if not defined
    */
   @Nullable
   public static String getProperty(
       String propertyName, @Nullable MavenProject project, @Nullable MavenSession session) {
-    if (session != null && session.getSystemProperties().containsKey(propertyName)) {
-      return session.getSystemProperties().getProperty(propertyName);
+    if (session != null && session.getUserProperties().containsKey(propertyName)) {
+      return session.getUserProperties().getProperty(propertyName);
     }
     if (project != null && project.getProperties().containsKey(propertyName)) {
       return project.getProperties().getProperty(propertyName);
     }
+    if (session != null && session.getSystemProperties().containsKey(propertyName)) {
+      return session.getSystemProperties().getProperty(propertyName);
+    }
     return null;
   }