I have a simple servlet that should return some commerce data. I have simplified the example here... but the issue is that if there is a link in any of the properties then I get invalid JSON and the link checker filter appears to altering the response even though I have disabled it via configuration.

package com.example.issue;
import org.apache.sling.api.SlingHttpServletRequest;
import org.apache.sling.api.SlingHttpServletResponse;
import org.apache.sling.api.resource.Resource;
import org.apache.sling.api.resource.ResourceResolver;
import org.apache.sling.api.resource.ValueMap;
import org.apache.sling.api.servlets.ServletResolverConstants;
import org.apache.sling.api.servlets.SlingAllMethodsServlet;
import org.json.JSONException;
import org.json.JSONObject;
import org.osgi.service.component.annotations.Component;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import javax.servlet.Servlet;
import javax.servlet.ServletException;
import java.io.IOException;
@Component(
    service= Servlet.class,
    property = {
            SimpleCommerceServlet.RESOURCE_TYPE_DEFAULT,
            SimpleCommerceServlet.SELECTOR,
            SimpleCommerceServlet.METHOD_GET,
            SimpleCommerceServlet.EXTENSION_JSON
    }
)
public class SimpleCommerceServlet extends SlingAllMethodsServlet {
    private static final long serialVersionUID = 1647028361800528653L;
    private static final Logger LOGGER = LoggerFactory.getLogger(SimpleCommerceServlet.class);
    public static final String RESOURCE_TYPE_DEFAULT = ServletResolverConstants.SLING_SERVLET_RESOURCE_TYPES + "=" + ServletResolverConstants.DEFAULT_RESOURCE_TYPE;
    public static final String EXTENSION_JSON = ServletResolverConstants.SLING_SERVLET_EXTENSIONS+"=json";
    public static final String METHOD_GET = ServletResolverConstants.SLING_SERVLET_METHODS + "=GET";
    public static final String SELECTOR = ServletResolverConstants.SLING_SERVLET_SELECTORS +"=getCommerceDetails";
    private ResourceResolver resourceResolver;
    @Override
    protected void doGet(SlingHttpServletRequest request, SlingHttpServletResponse response) throws ServletException, IOException {
        try {
            resourceResolver = request.getResourceResolver();
            Resource resource = resourceResolver.getResource("/etc/commerce/products/we-retail/custom/sample_product");
            JSONObject jsonObject = new JSONObject();
            ValueMap vm = resource.adaptTo(ValueMap.class);
            jsonObject.put("Title", vm.get("jcr:title"));
            jsonObject.put("Summary", vm.get("summary"));
            response.setHeader("Content-Type", "application/json");
            response.setCharacterEncoding("UTF-8");
            response.getWriter().write(jsonObject.toString());
        } catch (JSONException  e) {
            LOGGER.error("Failed to get and process JSON");
        } finally {
            resourceResolver.close();
        }
    }
}

I have created a new product at /etc/commerce/products/we-retail/custom/sample_product with properties

jcr:title = Sample Product

summary =

<p>This is a summary but it also has a <a title="Google" href="https://www" target="_blank">link</a>.</p>

Calling the Servlet like:
http://localhost:8080/bin/commerce.getCommerceDetails.details.json 

Results in invalid json

{"Title":"Sample Product","Summary":"<p>This is a summary but it also has a <img src="/libs/cq/linkchecker/resources/linkcheck_o.gif" alt="invalid link: Google\\" title="invalid link: Google\\" border="0">link<\/a>.<\/p>\r\n"}

Note the insertion of the linkcheck gif!

I have tried using LinkCheckerSetting to ignore Internal and External.

I have disabled link checking and rewriting via com.day.cq.rewriter.linkchecker.impl.LinkCheckerTransformerFactory

I have changed the Link Check Override to ^. in com.day.cq.rewriter.linkchecker.impl.LinkCheckerImpl

Any other ideas on how to prevent the Link Checker from changing the response of this Servlet?

I'm running AEM 6.3 SP1