[FLINK-12459][yarn] YarnConfigOptions#CLASSPATH_INCLUDE_USER_JAR shou…

…ld affect the order of classpath between user jars and flink jars

Put user code jars behind the Flink distribution jar when setting
YarnConfigOptions#CLASSPATH_INCLUDE_USER_JAR to "LAST".

This closes apache#8395.

flink-yarn/src/main/java/org/apache/flink/yarn/AbstractYarnClusterDescriptor.java

@@ -786,11 +786,6 @@ public ApplicationReport startAppMaster(
 		for (String classPath : systemClassPaths) {
 			classPathBuilder.append(classPath).append(File.pathSeparator);
 		}
-		if (userJarInclusion == YarnConfigOptions.UserJarInclusion.LAST) {
-			for (String userClassPath : userClassPaths) {
-				classPathBuilder.append(userClassPath).append(File.pathSeparator);
-			}
-		}
 
 		// Setup jar for ApplicationMaster
 		Path remotePathJar = setupSingleLocalResource(
@@ -831,6 +826,12 @@ public ApplicationReport startAppMaster(
 		paths.add(remotePathConf);
 		classPathBuilder.append("flink-conf.yaml").append(File.pathSeparator);
 
+		if (userJarInclusion == YarnConfigOptions.UserJarInclusion.LAST) {
+			for (String userClassPath : userClassPaths) {
+				classPathBuilder.append(userClassPath).append(File.pathSeparator);
+			}
+		}
+
 		// write job graph to tmp file and add it to local resource
 		// TODO: server use user main method to generate job graph
 		if (jobGraph != null) {