refactor(OAIService): solve code inspection issues

solidify-oai-pmh/src/main/java/ch/unige/solidify/service/OAIService.java

@@ -92,9 +92,7 @@ import ch.unige.solidify.util.XMLTool;
 @ConditionalOnBean(OAIController.class)
 public class OAIService {
 
-  private JAXBContext jaxbContext;
-  private List<Class<?>> xmlClasses = new ArrayList<>(Arrays.asList(OAIPMHtype.class, OaiDcType.class, OaiIdentifierType.class, Html.class));
-
+  private final JAXBContext jaxbContext;
   private final int oaiPmhPageSize;
   private final int oaiPmhTokenLifeTime;
 
@@ -128,8 +126,9 @@ public class OAIService {
     // JAXB contexts
     try {
       // Add project XML Classes
-      this.xmlClasses.addAll(this.metadataService.getOaiXmlClasses());
-      this.jaxbContext = JAXBContext.newInstance(this.xmlClasses.toArray(Class<?>[]::new));
+      final List<Class<?>> xmlClasses = new ArrayList<>(Arrays.asList(OAIPMHtype.class, OaiDcType.class, OaiIdentifierType.class, Html.class));
+      xmlClasses.addAll(this.metadataService.getOaiXmlClasses());
+      this.jaxbContext = JAXBContext.newInstance(xmlClasses.toArray(Class<?>[]::new));
     } catch (JAXBException e) {
       throw new SolidifyRuntimeException(e.getMessage(), e);
     }
@@ -228,10 +227,6 @@ public class OAIService {
     return VerbType.fromValue(verb);
   }
 
-  public VerbType[] getVerbs() {
-    return VerbType.values();
-  }
-
   public ListIdentifiersType listIdentifiers(String metadataPrefix, String from, String until, String set, String token) {
     // Check Parameters
     final OAIToken oaiToken = this.checkParameters(metadataPrefix, from, until, set, token);