FINERACT-1975: BatchAPI - JSON handler cannot handle null (fix)

fineract-core/src/main/java/org/apache/fineract/batch/service/ResolutionHelper.java

@@ -182,6 +182,9 @@ public class ResolutionHelper {
         } else if (element.isJsonArray()) {
             final JsonArray jsElementArray = element.getAsJsonArray();
             value = processJsonArray(jsElementArray, responseCtx);
+        } else if (element.isJsonNull()) {
+            // No further processing of null values
+            value = element;
         } else {
             value = resolveDependentVariable(element, responseCtx);
         }

integration-tests/src/test/java/org/apache/fineract/integrationtests/common/BatchHelper.java

@@ -820,9 +820,8 @@ public final class BatchHelper {
         br.setRelativeUrl(String.format("v1/loans/$.loanId/transactions?command=%s", transactionCommand));
         br.setMethod("POST");
         String dateString = date.format(DateTimeFormatter.ofPattern("dd MMMM yyyy"));
-        br.setBody(String.format(
-                "{\"locale\": \"en\", \"dateFormat\": \"dd MMMM yyyy\", " + "\"transactionDate\": \"%s\",  \"transactionAmount\": %s}",
-                dateString, amount));
+        br.setBody(String.format("{\"locale\": \"en\", \"dateFormat\": \"dd MMMM yyyy\", "
+                + "\"transactionDate\": \"%s\",  \"transactionAmount\": %s, \"note\":null}", dateString, amount));
 
         return br;
     }