HBASE-28961 Add essential build plugins to hbase-diagnostics (#6444)

Signed-off-by: Istvan Toth <stoty@apache.org>
(cherry picked from commit 40d9e9d)

Author: NihalJain

hbase-diagnostics/pom.xml

@@ -187,4 +187,41 @@
       <scope>test</scope>
     </dependency>
   </dependencies>
+
+  <build>
+    <plugins>
+      <plugin>
+        <!--Make it so assembly:single does nothing in here-->
+        <artifactId>maven-assembly-plugin</artifactId>
+        <configuration>
+          <skipAssembly>true</skipAssembly>
+        </configuration>
+      </plugin>
+      <!-- Make a jar and put the sources in the jar -->
+      <plugin>
+        <groupId>org.apache.maven.plugins</groupId>
+        <artifactId>maven-source-plugin</artifactId>
+        <executions>
+          <execution>
+            <goals>
+              <goal>jar</goal>
+              <goal>test-jar</goal>
+            </goals>
+            <phase>package</phase>
+          </execution>
+        </executions>
+      </plugin>
+      <plugin>
+        <groupId>org.apache.maven.plugins</groupId>
+        <artifactId>maven-checkstyle-plugin</artifactId>
+        <configuration>
+          <failOnViolation>true</failOnViolation>
+        </configuration>
+      </plugin>
+      <plugin>
+        <groupId>net.revelc.code</groupId>
+        <artifactId>warbucks-maven-plugin</artifactId>
+      </plugin>
+    </plugins>
+  </build>
 </project>

hbase-diagnostics/src/main/java/org/apache/hadoop/hbase/util/MultiThreadedWriter.java

@@ -34,10 +34,12 @@
 import org.apache.hadoop.hbase.client.Table;
 import org.apache.hadoop.hbase.util.test.LoadTestDataGenerator;
 import org.apache.hadoop.util.StringUtils;
+import org.apache.yetus.audience.InterfaceAudience;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
 /** Creates multiple threads that write key/values into the */
+@InterfaceAudience.Private
 public class MultiThreadedWriter extends MultiThreadedWriterBase {
   private static final Logger LOG = LoggerFactory.getLogger(MultiThreadedWriter.class);