code: public static Map makeMap(Mapper mapper, Object[] a) {
          return makeMap(mapper, java.util.Arrays.asList(a), false);
      }
docs: Create a new Map by using the array objects as keys, and the mapping result as values. Discard keys which return
  null values from the mapper.
  
  @param mapper a Mapper to map the values
  @param a      array of items
  
  @return a new Map with values mapped