public boolean contains(String key, String value) {
        List<String> lst = content.get(key);
        if (lst == null) {
            return false;
        }
        return lst.contains(value);
    }
<p>Convenience method for checking whether or not a named header contains a specific value. If the named header
is not set, or if the given value is not contained within that header's value list, this method returns
<em>false</em>.</p>

<p><em>NOTE:</em> This method is case-SENSITIVE.</p>

@param key   The key whose values to search in.
@param value The values to search for.
@return True if the given value was found in the named header.
@see #containsIgnoreCase
jdisc_core/src/main/java/com/yahoo/jdisc/HeaderFields.java