Guard GelfTCPSSLSender.closeSocketChannel against uninitialized SSLEn…

…gine #111

Do not interact with SSLEngine if SSLEngine is not available. This can happen if the sender is closed without establishing a connection prior closing.

Original pull request: #112.

src/main/java/biz/paluch/logging/gelf/intern/sender/GelfTCPSSLSender.java

@@ -261,9 +261,11 @@ public void close() {
     }
 
     private void closeSocketChannel() throws IOException {
-
-        sslEngine.closeOutbound();
-        doHandshake(channel(), sslEngine, ByteBuffer.allocate(sslSession.getPacketBufferSize()),
-                ByteBuffer.allocate(sslSession.getPacketBufferSize()));
+
+    	if(sslEngine != null){
+    		sslEngine.closeOutbound();
+    		doHandshake(channel(), sslEngine, ByteBuffer.allocate(sslSession.getPacketBufferSize()),
+    				ByteBuffer.allocate(sslSession.getPacketBufferSize()));
+    	}
     }
 }