@Before
  public void initEnvMap() {
    envMap.clear();
    envMap.putAll(DEFAULTS);
  }
This is a hack to make environment variables modifiable.
Ref: https://stackoverflow.com/questions/318239/how-do-i-set-environment-variables-from-java.
itests/hive-unit/src/test/java/org/apache/hive/service/auth/jwt/TestHttpJwtAuthentication.java