public Integer getEntryCount() {
      if (type == EvictionType.ENTRY_COUNT) {
        return limit;
      }
      return null;
    }
once a type is set, it can not be changed to another value.

@param type eviction type
@throws IllegalArgumentException if type is already set to another value. this is to
        prevent users from trying to send in conflicting attributes in json
        format such as {entryCount:10,type:HEAP_PERCENTAGE}
geode-management/src/main/java/org/apache/geode/management/configuration/Region.java