added statics for default content type and encoding

src/net/java/sip/communicator/service/protocol/OperationSetBasicInstantMessaging.java

@@ -16,6 +16,16 @@
 public interface OperationSetBasicInstantMessaging
     extends OperationSet
 {
+    /**
+     * Default encoding for outgoing messages.
+     */
+    public static final String DEFAULT_MIME_ENCODING = "UTF-8";
+
+    /**
+     * Default mime type for outgoing messages.
+     */
+    public static final String DEFAULT_MIME_TYPE = "text/plain";
+
     /**
      * Create a Message instance for sending arbitrary MIME-encoding content.
      *