public LdapUsernameCollisionHandlingBehavior getLdapSyncCollisionHandlingBehavior() {
    return LdapUsernameCollisionHandlingBehavior.translate(
        getProperty(LDAP_SYNC_USERNAME_COLLISIONS_BEHAVIOR),
        LdapUsernameCollisionHandlingBehavior.ADD);
  }
Determines whether an existing local users will be skipped on updated during LDAP sync.

@return true if ambari need to skip existing user during LDAP sync.
ambari-server/src/main/java/org/apache/ambari/server/configuration/Configuration.java