add untested way to reject (i.e., discard) a value to be send

ragconnect.base/src/main/resources/mappingApplication.mustache

@@ -3,6 +3,9 @@ try {
   {{#InnerMappingDefinitions}}
   {{^last}}{{toType}} {{/last}}{{outputVarName}} = {{methodName}}({{inputVarName}});
   {{/InnerMappingDefinitions}}
+} catch (RagConnectRejectMappingException e) {
+  // do not print message in case of rejection
+  {{preemptiveReturn}}
 } catch (Exception e) {
   e.printStackTrace();
   {{preemptiveReturn}}

ragconnect.base/src/main/resources/ragconnect.mustache

@@ -17,6 +17,11 @@ aspect RagConnect {
   {{> sendDefinition}}
   {{/TypeSendDefinitions}}
 
+  class RagConnectRejectMappingException extends RuntimeException {}
+  private static void ASTNode.reject() {
+    throw new RagConnectRejectMappingException();
+  }
+
   {{#MappingDefinitions}}
   {{#isUsed}}
   {{> mappingDefinition}}