void forEach(
void f(String name, List<String> values)
)

Enumerates the headers, applying the function f to each header. The header name passed in name will be all lower case.

Source

/**
 * Enumerates the headers, applying the function [f] to each
 * header. The header name passed in [:name:] will be all lower
 * case.
 */
void forEach(void f(String name, List<String> values));