private Predicate toPredicate(String predicate) {
    Predicate compiledPredicate = null;
    try {
      if (predicate != null && ! predicate.isEmpty()) {
        compiledPredicate = predicateCompiler.compile(predicate);
      }
    } catch (InvalidQueryException e) {
      // log error and proceed without predicate
      LOG.error("Unable to compile predicate for host request: " + e, e);
    }
    return compiledPredicate;
  }
Only to be used when replaying persisted requests upon server startup.

@param requestId    logical request id
@param id           host request id
@param predicate    host predicate
@param topology     cluster topology
@param entity       host request entity
ambari-server/src/main/java/org/apache/ambari/server/topology/HostRequest.java