@Override
    void onClear() {
        contentLengthMayBeUnknown = false;
        if (cache == null || cache.isEmpty()) {
            return;
        }
        // Invalidate all cached values
        cache.clear();
    }
Creates a deep copy of the specified {@link HttpHeaderGetters}.
core/src/main/java/com/linecorp/armeria/common/HttpHeadersBase.java