private TableName createTable(String table) throws IOException {
    TableName tableName = TableName.valueOf(table);
    TEST_UTIL.createTable(tableName, FAMILYNAME);
    return tableName;
  }
Before HBASE-26712,here invokes {@link AssignmentManager#balance(RegionPlan)} which may
throw NPE.
hbase-server/src/test/java/org/apache/hadoop/hbase/master/TestMasterBalancerNPE.java