@Nullable
    private static Long toLong(@Nullable String v) {
        try {
            return v != null ? Long.parseLong(v) : null;
        } catch (NumberFormatException ignore) {
            return null;
        }
    }
Removes all the entries whose hash code equals {@code h} and whose name is equal to {@code name}.

@return the first value inserted, or {@code null} if there is no such entry.
core/src/main/java/com/linecorp/armeria/common/StringMultimap.java