code: public boolean contains(T value) {
  
          Boolean isMember = m_membershipMap.get(value);
          if (isMember != null) {
              return isMember.booleanValue();
          } else {
              return m_defaultMembership;
          }
      }
docs: Returns true if the given object is a member of this set.<p>
  
  @param value the value to check
  
  @return true  if the value is a member