🐛 Fix failures discovered discovered during integration testing

Server checks the template content type, should be XDP or PDF.

Import can return nothing, we were throwing error, but should return
empty document so that it can later be turned back into empty Optional.

Author: rmcdouga

rest-services/client/src/main/java/com/_4point/aem/docservices/rest_services/client/RestClient.java

@@ -145,8 +145,10 @@ default <T> Builder transformAndAddDocs(String fieldName, T fieldData, Function<
 				return fieldData != null ? addDocsIfNotNull(fieldName, fn.apply(fieldData)) : this;
 			}
 			default Builder addStringVersion(String fieldName, List<?> fieldData) {
-				for (Object obj : fieldData) {
-					addStringVersion(fieldName, obj);
+				if (fieldData != null) {
+					for (Object obj : fieldData) {
+						addStringVersion(fieldName, obj);
+					}
 				}
 				return this;
 			}

rest-services/client/src/main/java/com/_4point/aem/docservices/rest_services/client/forms/RestServicesFormsServiceAdapter.java

@@ -18,6 +18,7 @@
 import com._4point.aem.fluentforms.api.forms.PDFFormRenderOptions;
 import com._4point.aem.fluentforms.api.forms.ValidationOptions;
 import com._4point.aem.fluentforms.api.forms.ValidationResult;
+import com._4point.aem.fluentforms.impl.SimpleDocumentFactoryImpl;
 import com._4point.aem.fluentforms.impl.forms.TraditionalFormsService;
 import com.adobe.fd.forms.api.DataFormat;
 
@@ -67,7 +68,7 @@ public Document exportData(Document pdfOrXdp, DataFormat dataFormat) throws Form
 
             return payload.postToServer(ContentType.APPLICATION_XML)
             			  .map(RestServicesServiceAdapter::responseToDoc)
-            			  .orElseThrow();
+            			  .orElse(SimpleDocumentFactoryImpl.emptyDocument());	// If there was no response, return an empty document.
         } catch (IOException e) {
             throw new FormsServiceException("I/O Error while exporting data. (" + exportDataRestClient.target() + ").", e);
         } catch (RestClientException e) {
@@ -101,7 +102,7 @@ private Document internalRenderPDFForm(String urlOrfilename, Document template,
     	var xci = pdfFormRenderOptions.getXci();
         try (MultipartPayload payload = renderFormRestClient.multipartPayloadBuilder()
                 .addIfNotNull(TEMPLATE_PARAM, urlOrfilename)							// Since this is internal, we know that one of these two will be null
-                .addIfNotNull(TEMPLATE_PARAM, template, ContentType.APPLICATION_XML)
+                .addIfNotNull(TEMPLATE_PARAM, template, ContentType.APPLICATION_XDP)
                 .addIfNotNull(DATA_PARAM, data, ContentType.APPLICATION_XML)
                 .addStringVersion(ACROBAT_VERSION_PARAM, pdfFormRenderOptions.getAcrobatVersion())
                 .addStringVersion(CACHE_STRATEGY_PARAM, pdfFormRenderOptions.getCacheStrategy())

rest-services/client/src/test/java/com/_4point/aem/docservices/rest_services/client/forms/RestServicesFormsServiceAdapterTest.java

@@ -176,7 +176,7 @@ void testRenderPDFForm_HappyPaths(RenderFormsHappyPath codePath) throws Exceptio
 		PDFFormRenderOptions pdfFormRenderOptions = codePath.emptyOptions ? new PDFFormRenderOptionsImpl() : getNonDefaultPdfRenderOptions();
 
 		when(mockPayloadBuilder.addIfNotNull(eq("template"), codePath.templateString ? eq(templateFilename) : isNull())).thenReturn(mockPayloadBuilder);
-		when(mockPayloadBuilder.addIfNotNull(eq("template"), codePath.templateString ? isNull() : same(templateDoc), eq(ContentType.APPLICATION_XML))).thenReturn(mockPayloadBuilder);
+		when(mockPayloadBuilder.addIfNotNull(eq("template"), codePath.templateString ? isNull() : same(templateDoc), eq(ContentType.APPLICATION_XDP))).thenReturn(mockPayloadBuilder);
 		when(mockPayloadBuilder.addIfNotNull(eq("data"), codePath.hasData ? same(data) : isNull(), eq(ContentType.APPLICATION_XML))).thenReturn(mockPayloadBuilder);
 		when(mockPayloadBuilder.addStringVersion(eq("renderOptions.acrobatVersion"), eq(pdfFormRenderOptions.getAcrobatVersion()))).thenReturn(mockPayloadBuilder);
 		when(mockPayloadBuilder.addStringVersion(eq("renderOptions.cacheStrategy"), eq(pdfFormRenderOptions.getCacheStrategy()))).thenReturn(mockPayloadBuilder);