enable Reproducible Builds

Signed-off-by: Hervé Boutemy <hboutemy@apache.org>

Author: hboutemy

pom.xml

@@ -43,6 +43,9 @@
 	</distributionManagement>
     <properties>
       <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+      <project.build.outputTimestamp>1675930644</project.build.outputTimestamp>
+      <maven.compiler.source>8</maven.compiler.source>
+      <maven.compiler.target>8</maven.compiler.target>
       <sonar.host.url>https://sonarcloud.io</sonar.host.url>
 	  <sonar.organization>spdx</sonar.organization>
 	  <sonar.projectKey>java-spdx-library</sonar.projectKey>
@@ -64,7 +67,7 @@
 					<plugin>
 		      			<groupId>org.apache.maven.plugins</groupId>
 		      			<artifactId>maven-gpg-plugin</artifactId>
-		      			<version>1.6</version>
+		      			<version>3.1.0</version>
 		      			<executions>
 		        			<execution>
 		          				<id>sign-artifacts</id>
@@ -178,10 +181,8 @@
 		<plugin>
 			<groupId>org.apache.maven.plugins</groupId>
 			<artifactId>maven-compiler-plugin</artifactId>
-			<version>3.6.1</version>
+			<version>3.11.0</version>
 			<configuration>
-				<source>1.8</source>
-				<target>1.8</target>
 				<encoding>${project.build.sourceEncoding}</encoding>
 				<showDeprecation>true</showDeprecation>
 				<showWarnings>true</showWarnings>
@@ -191,11 +192,10 @@
 		<plugin>
 			<groupId>org.apache.maven.plugins</groupId>
 			<artifactId>maven-javadoc-plugin</artifactId>
-			<version>3.2.0</version>
+			<version>3.5.0</version>
 			<configuration>
 				<quiet>true</quiet>
-				<source>8</source>
-				<javadocExecutable>${env.JAVA_HOME}/bin/javadoc</javadocExecutable>
+                <notimestamp>true</notimestamp>
 				<additionalparam>-Xdoclint:none</additionalparam>
 			</configuration>
 			<executions>
@@ -212,8 +212,13 @@
 		</plugin>
 	   	<plugin>
 	      <groupId>org.apache.maven.plugins</groupId>
+	      <artifactId>maven-jar-plugin</artifactId>
+	      <version>3.3.0</version>
+		</plugin>
+	   	<plugin>
+	      <groupId>org.apache.maven.plugins</groupId>
 	      <artifactId>maven-source-plugin</artifactId>
-	      <version>3.2.1</version>
+	      <version>3.3.0</version>
 	      <executions>
 	        <execution>
 	          <id>attach-sources</id>