code: public Enumeration getHeaderNames() {
          // 321485
          if (TraceComponent.isAnyTracingEnabled()&&logger.isLoggable (Level.FINE)) {  //306998.15
              logger.logp(Level.FINE, CLASS_NAME,"getHeaderNames", "this->"+this+": ");
          }
  
          if (WCCustomProperties.CHECK_REQUEST_OBJECT_IN_USE){
              checkRequestObjectInUse();
          }
          // PK80362 Start
          if( suppressHeadersInRequest == null){        	            
              return _request.getHeaderNames();
          }
          else {// step through the existing enumeration and create a new one without header names listed in custom property     	
              ArrayList alHeaderNames = new ArrayList();
              Enumeration enumHeaderNames = _request.getHeaderNames();
              while( enumHeaderNames.hasMoreElements() ){
                  String headerNameParam = (String) enumHeaderNames.nextElement();
                  if (!(isHeaderinSuppressedHeadersList(headerNameParam)))
                      alHeaderNames.add(headerNameParam);
              }
              return Collections.enumeration(alHeaderNames); // create new Enumeration
          }
          // return _request.getHeaderNames();
          // PK80362 End
      }
docs: Returns an enumeration of strings representing the header names
  for this request. Some server implementations do not allow headers
  to be accessed in this way, in which case this method will return null.