have dataset page get cached JSON-LD, if available IQSS#3700

src/main/java/edu/harvard/iq/dataverse/DatasetPage.java

@@ -86,6 +86,7 @@
 import edu.harvard.iq.dataverse.engine.command.impl.RestrictFileCommand;
 import edu.harvard.iq.dataverse.engine.command.impl.ReturnDatasetToAuthorCommand;
 import edu.harvard.iq.dataverse.engine.command.impl.SubmitDatasetForReviewCommand;
+import edu.harvard.iq.dataverse.export.SchemaDotOrgExporter;
 import java.util.Collections;
 
 import javax.faces.event.AjaxBehaviorEvent;
@@ -4068,7 +4069,15 @@ public boolean isThisLatestReleasedVersion() {
 
     public String getJsonLd() {
         if (isThisLatestReleasedVersion()) {
-            return workingVersion.getJsonLd();
+            ExportService instance = ExportService.getInstance(settingsService);
+            String jsonLd = instance.getExportAsString(dataset, SchemaDotOrgExporter.NAME);
+            if (jsonLd != null) {
+                logger.fine("Returning cached schema.org JSON-LD.");
+                return jsonLd;
+            } else {
+                logger.fine("No cached schema.org JSON-LD available. Going to the database.");
+                return workingVersion.getJsonLd();
+            }
         }
         return "";
     }

src/main/java/edu/harvard/iq/dataverse/DatasetVersion.java

@@ -1211,12 +1211,8 @@ public String getPublicationDateAsString() {
         return r;
     }
 
-    // TODO: Make this more performant by writing the output to the database or a file?
-    // Agree - now that this has grown into a somewhat complex chunk of formatted
-    // metadata - and not just a couple of values inserted into the page html -
-    // it feels like it would make more sense to treat it as another supported  
-    // export format, that can be produced once and cached. 
-    // The problem with that is that the export subsystem assumes there is only 
+    // TODO: Consider moving this comment into the Exporter code.
+    // The export subsystem assumes there is only
     // one metadata export in a given format per dataset (it uses the current 
     // released (published) version. This JSON fragment is generated for a 
     // specific released version - and we can have multiple released versions. 

src/main/java/edu/harvard/iq/dataverse/export/SchemaDotOrgExporter.java

@@ -17,6 +17,8 @@ public class SchemaDotOrgExporter implements Exporter {
 
     private static final Logger logger = Logger.getLogger(SchemaDotOrgExporter.class.getCanonicalName());
 
+    public static final String NAME = "schema.org";
+
     @Override
     public void exportDataset(DatasetVersion version, JsonObject json, OutputStream outputStream) throws ExportException {
         String jsonLdAsString = version.getJsonLd();
@@ -37,7 +39,7 @@ public void exportDataset(DatasetVersion version, JsonObject json, OutputStream
 
     @Override
     public String getProviderName() {
-        return "schema.org";
+        return NAME;
     }
 
     @Override