Port log4j-flume-ng changes from 2.x

Author: vy

log4j-flume-ng/src/main/java/org/apache/logging/log4j/flume/appender/FlumeAvroManager.java

@@ -110,7 +110,6 @@ public static FlumeAvroManager getManager(
         if (batchSize <= 0) {
             batchSize = 1;
         }
-        ;
         final StringBuilder sb = new StringBuilder(name);
         sb.append(" FlumeAvro[");
         boolean first = true;
@@ -221,7 +220,7 @@ public void send(final Event event) {
         } else {
             int eventCount;
             BatchEvent batch = null;
-            synchronized (batchEvent) {
+            synchronized (this) {
                 batchEvent.addEvent(event);
                 eventCount = batchEvent.size();
                 final long now = System.nanoTime();

log4j-flume-ng/src/main/java/org/apache/logging/log4j/flume/appender/FlumeEmbeddedManager.java

@@ -38,7 +38,7 @@ public class FlumeEmbeddedManager extends AbstractFlumeManager {
 
     private static final String IN_MEMORY = "InMemory";
 
-    private static final FlumeManagerFactory factory = new FlumeManagerFactory();
+    private static final FlumeManagerFactory FACTORY = new FlumeManagerFactory();
 
     private final EmbeddedAgent agent;
 
@@ -78,11 +78,11 @@ public static FlumeEmbeddedManager getManager(
             throw new IllegalArgumentException("Cannot configure both Agents and Properties.");
         }
 
-        final String managerName = createManagerName(name, agents, properties);
-        return getManager(managerName, factory, new FactoryData(name, agents, properties, batchSize, dataDir));
+        final String extendedName = extendManagerName(name, agents, properties);
+        return getManager(extendedName, FACTORY, new FactoryData(name, agents, properties, batchSize, dataDir));
     }
 
-    private static String createManagerName(final String name, final Agent[] agents, final Property[] properties) {
+    private static String extendManagerName(final String name, final Agent[] agents, final Property[] properties) {
 
         final StringBuilder sb = new StringBuilder();
         boolean first = true;

log4j-flume-ng/src/main/java/org/apache/logging/log4j/flume/appender/FlumeEvent.java

@@ -295,7 +295,7 @@ public long getTimeMillis() {
 
     /**
      * {@inheritDoc}
-     * @since 2.11.0
+     * @since 2.11
      */
     @Override
     public Instant getInstant() {