Mark some Command params as nullable.

Change-Id: I6817cf188e01490b991d1e0db6f58c975957f634
Reviewed-on: http://gerrit.dmdirc.com/3949
Automatic-Compile: DMDirc Build Manager
Reviewed-by: Greg Holmes <greg@dmdirc.com>

src/com/dmdirc/commandparser/commands/Command.java

@@ -29,6 +29,7 @@ import com.dmdirc.interfaces.CommandController;
 import com.dmdirc.ui.messages.Styliser;
 
 import javax.annotation.Nonnull;
+import javax.annotation.Nullable;
 
 /**
  * Represents a generic command.
@@ -58,7 +59,7 @@ public abstract class Command {
      * @param type     The type of message to send
      * @param args     The arguments of the message
      */
-    protected final void sendLine(final FrameContainer target,
+    protected final void sendLine(@Nullable final FrameContainer target,
             final boolean isSilent, final String type, final Object... args) {
         if (!isSilent && target != null) {
             target.addLine(type, args);
@@ -73,7 +74,7 @@ public abstract class Command {
      * @param name     The name of the command that's raising the error
      * @param args     The arguments that the command accepts or expects
      */
-    protected final void showUsage(final FrameContainer target,
+    protected final void showUsage(@Nullable final FrameContainer target,
             final boolean isSilent, final String name, final String args) {
         sendLine(target, isSilent, "commandUsage",
                 controller.getCommandChar(),