Fix some generics compiler warnings.

log4j-api/src/main/java/org/apache/logging/log4j/message/MapMessage.java

@@ -146,6 +146,7 @@ public class MapMessage<M extends MapMessage<M, V>, V> implements MultiformatMes
      * Returns the message data as an unmodifiable Map.
      * @return the message data as an unmodifiable map.
      */
+    @SuppressWarnings("unchecked")
     public Map<String, V> getData() {
         final TreeMap<String, V> result = new TreeMap<>(); // returned map must be sorted
         for (int i = 0; i < data.size(); i++) {

log4j-core/src/main/java/org/apache/logging/log4j/core/filter/MapFilter.java

@@ -67,7 +67,7 @@ public class MapFilter extends AbstractFilter {
     public Result filter(final Logger logger, final Level level, final Marker marker, final Message msg,
                          final Throwable t) {
         if (msg instanceof MapMessage) {
-            return filter((MapMessage) msg) ? onMatch : onMismatch;
+            return filter((MapMessage<?, ?>) msg) ? onMatch : onMismatch;
         }
         return Result.NEUTRAL;
     }
@@ -76,12 +76,12 @@ public class MapFilter extends AbstractFilter {
     public Result filter(final LogEvent event) {
         final Message msg = event.getMessage();
         if (msg instanceof MapMessage) {
-            return filter((MapMessage) msg) ? onMatch : onMismatch;
+            return filter((MapMessage<?, ?>) msg) ? onMatch : onMismatch;
         }
         return Result.NEUTRAL;
     }
 
-    protected boolean filter(final MapMessage mapMessage) {
+    protected boolean filter(final MapMessage<?, ?> mapMessage) {
         boolean match = false;
         for (int i = 0; i < map.size(); i++) {
             final String toMatch = mapMessage.get(map.getKeyAt(i));

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

@@ -36,7 +36,6 @@ import org.apache.logging.log4j.core.util.Patterns;
 import org.apache.logging.log4j.core.util.UuidUtil;
 import org.apache.logging.log4j.message.MapMessage;
 import org.apache.logging.log4j.message.Message;
-import org.apache.logging.log4j.message.StringMapMessage;
 import org.apache.logging.log4j.message.StructuredDataId;
 import org.apache.logging.log4j.message.StructuredDataMessage;
 import org.apache.logging.log4j.util.ReadOnlyStringMap;