fix: force http usage, in order to be compatible with old XML validators

solidify-oai-pmh/src/main/java/ch/unige/solidify/controller/oai/OAIProviderController.java

@@ -115,9 +115,11 @@ public class OAIProviderController implements ControllerWithHateoasHome {
           // OAI Identifier
           schemaLocations.put(OAIConstants.OAI_ID_NAMESPACE, OAIConstants.OAI_ID_SCHEMA);
           // OAI Repository
+          // Force http usage, in order to be compatible with old XML validators
+          final String httpOnlyOaiUrl = oaiUrl.replace("https://", "http://");
           schemaLocations.put(
                   this.oaiService.getOaiRepositoryInfo().getRepositoryNamepsace(),
-                  oaiUrl + SolidifyConstants.URL_SEP + SolidifyConstants.SCHEMA);
+                  httpOnlyOaiUrl + SolidifyConstants.URL_SEP + SolidifyConstants.SCHEMA);
           break;
         case LIST_IDENTIFIERS:
           // Specification