@Parameters
  public static Collection<Object[]> getParameters() {
    List<Object[]> cowTypes = new ArrayList<>();
    for (CacheOnWriteType cowType : CacheOnWriteType.values()) {
      cowTypes.add(new Object[] { cowType });
    }
    return cowTypes;
  }
The number of valid key types possible in a store file
hbase-server/src/test/java/org/apache/hadoop/hbase/regionserver/TestCacheOnWriteInSchema.java