JAVA-425: WriteConcern in "Default" (W < 0) passes through empty getLastError to allow use of getLastErrorDefaults setting on server

Author: Brendan W. McAdams

src/main/com/mongodb/WriteConcern.java

@@ -242,8 +242,10 @@ public WriteConcern( String w , int wtimeout , boolean fsync, boolean j , Boolea
     public BasicDBObject getCommand(){
         BasicDBObject _command = new BasicDBObject( "getlasterror" , 1 );
 
-        _command.put( "w" , _wValue );
-        _command.put( "wtimeout" , _wtimeout );
+        if ( _wValue instanceof Integer && ( (Integer) _wValue > 0) ){
+            _command.put( "w" , _wValue );
+            _command.put( "wtimeout" , _wtimeout );
+        }
 
         if ( _fsync )
             _command.put( "fsync" , true );