@SafeVarargs
  public static String FLOAT(String key, Predicate<Float>... predicates) {
    return register(key,
      conf -> validateNumeric(key, "a float", () -> conf.getFloat(key, 0), predicates));
  }
Registers the configuration key that expects a float.
@param key        configuration key
@param predicates additional predicates to validate the value
@return the key
hbase-common/src/main/java/org/apache/hadoop/hbase/conf/ConfigKey.java