Deprecate MongoNamespace#COMMAND_COLLECTION_NAME (#1786)

JAVA-5943

Author: jyemin

driver-core/src/main/com/mongodb/MongoNamespace.java

@@ -37,7 +37,10 @@
 public final class MongoNamespace {
     /**
      * The collection name in which to execute a command.
+     * @deprecated there is no replacement for this constant, as it is only needed for the OP_QUERY wire protocol message, which has
+     * been replaced by OP_MSG
      */
+    @Deprecated
     public static final String COMMAND_COLLECTION_NAME = "$cmd";
 
     private static final Set<Character> PROHIBITED_CHARACTERS_IN_DATABASE_NAME =