code: public static SpreadMap toSpreadMap(Iterable self) {
          if (self == null)
              throw new GroovyRuntimeException("Fail to convert Iterable to SpreadMap, because it is null.");
          else
              return toSpreadMap(asList(self));
      }
docs: Creates a spreadable map from this iterable.
  <p>
  @param self an iterable
  @return a newly created SpreadMap
  @see groovy.lang.SpreadMap#SpreadMap(java.util.List)
  @see #toSpreadMap(java.util.Map)
  @since 2.4.0