private void ensureDb(String dbName) {
        Map<String, Set<LinkedHashMap<String, String>>> tables = entities.get(dbName);
        if (tables == null) {
          tables = new HashMap<>();
          entities.put(dbName, tables);
        }
      }
Lets callers specify what entities are requested to be evicted, and builds a Request instance accordingly.
ql/src/java/org/apache/hadoop/hive/llap/ProactiveEviction.java