public Request addRequestHeader(String header,String value){
  if (header == null) {
    throw new NullPointerException("header cannot be null");
  }
  if (header.contains(":")) {
    throw new IllegalArgumentException("header may not contain ':'");
  }
  if (value == null) {
    value="";
  }
  requestHeaders.add(Pair.create(header,value));
  return this;
}

public Request addRequestHeader ( String header , String value ) { if ( header == null ) { throw new NullPointerException ( "header cannot be null" ) ; } if ( header . contains ( ":" ) ) { throw new IllegalArgumentException ( "header may not contain ':'" ) ; } if ( value == null ) { value = "" ; } requestHeaders . add ( Pair . create ( header , value ) ) ; return this ; }
add an http header to be included with the download request . the header will be added to the end of the list .
