Don't repeat exception cause message when attaching the exception to …

…the status

The default "OnConsoleStatusListener" already appends the cause's message when printing tth status on the console. Addining it in the original message will cause duplicates on the console.
Those not relying on the "OnConsoleStatusLisener" should simply retrieve additional information from the status  throwable if any (what they probaby already do for ErrorStatus anyway...)

src/main/java/net/logstash/logback/appender/AbstractLogstashTcpSocketAppender.java

@@ -574,7 +574,7 @@ public void onEvent(LogEvent<Event> logEvent, long sequence, boolean endOfBatch)
                     /*
                      * Encoding threw an exception. Warn and drop event before it becomes a "poison".
                      */
-                    addWarn(peerId + "Encoder failed to encode event: " + e.getMessage() + ". Dropping event.", e.getCause());
+                    addWarn(peerId + "Encoder failed to encode event. Dropping event.", e.getCause());
                     fireEventSendFailure(logEvent.event, e.getCause());
                     break;
 
@@ -583,7 +583,7 @@ public void onEvent(LogEvent<Event> logEvent, long sequence, boolean endOfBatch)
                      * Any other exception is thrown by the socket stream (or bug in the code).
                      * Re-open the socket and get a fresh new stream.
                      */
-                    addWarn(peerId + "Unable to send event: " + e.getMessage() + ". Reconnecting.", e);
+                    addWarn(peerId + "Unable to send event. Reconnecting.", e);
                     reopenSocket();
                 }
             }

src/test/java/net/logstash/logback/appender/LogstashTcpSocketAppenderTest.java

@@ -657,7 +657,7 @@ public void testEncoderThrowsException() throws Exception {
         // A warn status is emitted
         assertThat(statusManager.getCopyOfStatusList()).anySatisfy(status -> {
             assertThat(status.getLevel()).isEqualTo(Status.WARN);
-            assertThat(status.getMessage()).contains("Encoder failed to encode event:");
+            assertThat(status.getMessage()).contains("Encoder failed to encode event. Dropping event.");
         });
     }
 
@@ -700,7 +700,7 @@ public void testStreamingEncoderThrowsException() throws Exception {
         // A warn status is emitted
         assertThat(statusManager.getCopyOfStatusList()).anySatisfy(status -> {
             assertThat(status.getLevel()).isEqualTo(Status.WARN);
-            assertThat(status.getMessage()).contains("Encoder failed to encode event:");
+            assertThat(status.getMessage()).contains("Encoder failed to encode event. Dropping event.");
         });
     }