We ran into a bug with apache 2.2.24, where content-length wasn't be set correctly because it's set as a header instead of using the struct.

394     else if (!strcasecmp(header_names[h], "Content-Length")) {
395         apr_table_set(r->headers_out, header_names[h], header_values[h]);
396     }
397     else if (!strcasecmp(header_names[h], "Transfer-Encoding")) {



This is a bug and needs to be something like:

else if (!strcasecmp(header_names[h], "Content-Length")) {
    ap_set_content_length(r, apr_atoi64(header_values[h]));
}

The problem is that mod_jk is setting the headers out, but not setting the
r->clength value.  Calling ap_set_content_length sets both.