Add body length change check - triggers exception

solr/solrj/src/java/org/apache/solr/client/solrj/impl/HttpJdkSolrClient.java

@@ -306,9 +306,11 @@ private PreparedRequest preparePutOrPost(
       // qP gains further (?) params moved from original set if solrRequest has params, but only if urlParamNames was set too
       queryParams.add(calculateQueryParams(solrRequest.getQueryParams(), requestParams));
       // bP receives any remaining params from original set
-      // with this version the params are not fully encoded - we get raw Unicode chars, curly braces etc
+      // with this version the params are not fully encoded - we get raw Unicode chars, curly braces etc - and the body content length changes, presumably due to re-encoding
       String bodyQueryString = requestParams.toString();
       bodyPublisher = HttpRequest.BodyPublishers.ofString(bodyQueryString);
+      // this isn't intended to be merged - but it shows the content length change noted above
+      if (bodyQueryString.length() != bodyPublisher.contentLength()) throw new URISyntaxException("inconsistent content length", bodyQueryString + " - " + bodyQueryString.length() + " -> " + bodyPublisher.contentLength());
       // qP has been replaced with params moved from original set
     } else {
       bodyPublisher = HttpRequest.BodyPublishers.noBody();