return;
        }
        adjustActionResponseHeaders(mimeType, (k, v) -> {
            if (logger.isDebugEnabled()) {
                logger.debug("Apply header: key={}, value={}, mimeType={}", k, v, mimeType);
            }
            response.header(k, v);
        });
    }

    protected void adjustActionResponseHeaders(final String mimeType, final BiConsumer<String, String> callback) {

        FessActionAdjustmentProvider provider = new FessActionAdjustmentProvider(fessConfig);
        final Map<String, String> headerMap = new HashMap<>();
        provider.adjustActionResponseHeaders("text/plain", (k, v) -> headerMap.put(k, v));

        assertEquals(0, headerMap.size());
    }

    @Test
    public void test_write_defaultHeadersOnly() throws Exception {