public void headerOut(String key,String value){
  Objects.requireNonNull(value);
  if (isOutCommitted()) {
    return;
  }
  if (headerOutSpecial(key,value)) {
    return;
  }
  setHeaderOutImpl(key,value);
}

public void headerOut ( String key , String value ) { Objects . requireNonNull ( value ) ; if ( isOutCommitted ( ) ) { return ; } if ( headerOutSpecial ( key , value ) ) { return ; } setHeaderOutImpl ( key , value ) ; }
sets a header , replacing an already - existing header .
