Merge branch 'pr-2444'

[core] Support reproducible builds #2444

BUILDING.md

@@ -18,6 +18,20 @@ That's all !
 
 **Note:** While Java 11 is required for building, running PMD only requires Java 7 (or Java 8 for Apex and the Designer).
 
+**Note:** With PMD 6.24.0, we are creating [Reproducible Builds](https://reproducible-builds.org/). Since we use
+[Maven](https://maven.apache.org/guides/mini/guide-reproducible-builds.html) for building, the following
+limitations apply:
+
+*   Generally give **different results on Windows and Unix** because of different newlines.
+    (carriage return linefeed on Windows, linefeed on Unixes).
+    
+    We build our releases under **Linux** on [Travis CI](https://travis-ci.org/pmd/pmd).
+
+*   Generally depend on the **major version of the JDK** used to compile. (Even with source/target defined,
+    each major JDK version changes the generated bytecode.).
+    
+    We build our releases using OpenJDK 11 (see "before_install" step in `.travis.yml`).
+
 ## How to build the documentation?
 
     cd docs

docs/pages/release_notes.md

@@ -37,6 +37,7 @@ This is useful to find duplicated sections in XML files.
 *   apex-bestpractices
     *   [#2468](https://github.com/pmd/pmd/issues/2468): \[apex] Unused Local Variable fails on blocks
 *   core
+    *   [#2444](https://github.com/pmd/pmd/pull/2444): \[core] Support reproducible builds
     *   [#2484](https://github.com/pmd/pmd/issues/2484): \[core] Update maven-enforcer-plugin to require Java 118
 *   java
     *   [#2472](https://github.com/pmd/pmd/issues/2472): \[java] JavaCharStream throws an Error on invalid escape

pom.xml

@@ -76,6 +76,8 @@
     </issueManagement>
 
     <properties>
+        <project.build.outputTimestamp>2020-04-25T00:00:00Z</project.build.outputTimestamp>
+
         <java.version>7</java.version>
 
         <maven.compiler.test.source>1.8</maven.compiler.test.source>
@@ -134,7 +136,7 @@
                 <plugin>
                     <groupId>org.apache.maven.plugins</groupId>
                     <artifactId>maven-assembly-plugin</artifactId>
-                    <version>3.1.0</version>
+                    <version>3.2.0</version>
                 </plugin>
                 <plugin>
                     <groupId>org.apache.maven.plugins</groupId>
@@ -144,7 +146,7 @@
                 <plugin>
                     <groupId>org.apache.maven.plugins</groupId>
                     <artifactId>maven-release-plugin</artifactId>
-                    <version>2.5.3</version>
+                    <version>3.0.0-M1</version>
                     <configuration>
                         <releaseProfiles>pmd-release,sign</releaseProfiles>
                         <pushChanges>true</pushChanges>
@@ -234,7 +236,7 @@
                 <plugin>
                     <groupId>org.apache.maven.plugins</groupId>
                     <artifactId>maven-jar-plugin</artifactId>
-                    <version>3.1.0</version>
+                    <version>3.2.0</version>
                 </plugin>
                 <plugin>
                     <groupId>org.apache.maven.plugins</groupId>
@@ -244,7 +246,7 @@
                 <plugin>
                     <groupId>org.apache.maven.plugins</groupId>
                     <artifactId>maven-shade-plugin</artifactId>
-                    <version>3.1.1</version>
+                    <version>3.2.3</version>
                 </plugin>
                 <plugin>
                     <groupId>org.apache.maven.plugins</groupId>
@@ -266,7 +268,7 @@
                 <plugin>
                     <groupId>org.apache.maven.plugins</groupId>
                     <artifactId>maven-source-plugin</artifactId>
-                    <version>3.0.1</version>
+                    <version>3.2.1</version>
                 </plugin>
                 <plugin>
                     <groupId>org.apache.maven.plugins</groupId>