private boolean prepareCreate(final MasterProcedureEnv env) throws IOException {
    if (getTableNamespaceManager(env).doesNamespaceExist(nsDescriptor.getName())) {
      setFailure("master-create-namespace",
        new NamespaceExistException("Namespace " + nsDescriptor.getName() + " already exists"));
      return false;
    }
    getTableNamespaceManager(env).validateTableAndRegionCount(nsDescriptor);
    checkNamespaceRSGroup(env, nsDescriptor);
    return true;
  }
Action before any real action of creating namespace.
@param env MasterProcedureEnv
hbase-server/src/main/java/org/apache/hadoop/hbase/master/procedure/CreateNamespaceProcedure.java