Improve RDF body mappers error message

Author: NSeydoux

jena/src/main/java/com/inrupt/client/jena/JenaBodyHandlers.java

@@ -49,7 +49,7 @@ public final class JenaBodyHandlers {
     private static void throwOnError(final Response.ResponseInfo responseInfo) {
         if (!Response.isSuccess(responseInfo.statusCode())) {
             throw new ClientHttpException(
-                    "Could not map to a Jena entity.",
+                    "An HTTP error was encountered mapping to a Jena entity.",
                     responseInfo.uri(),
                     responseInfo.statusCode(),
                     responseInfo.headers(),

rdf4j/src/main/java/com/inrupt/client/rdf4j/RDF4JBodyHandlers.java

@@ -46,7 +46,7 @@ public final class RDF4JBodyHandlers {
     private static void throwOnError(final Response.ResponseInfo responseInfo) {
         if (!Response.isSuccess(responseInfo.statusCode())) {
             throw new ClientHttpException(
-                    "Could not map to an RDF4J entity.",
+                    "An HTTP error was encountered mapping to an RDF4J entity.",
                     responseInfo.uri(),
                     responseInfo.statusCode(),
                     responseInfo.headers(),