Add Singleton annotations

Author: leonardehrenfried

application/src/main/java/org/opentripplanner/routing/linking/configure/VertexLinkerGraphBuildingModule.java

@@ -2,6 +2,7 @@
 
 import dagger.Module;
 import dagger.Provides;
+import jakarta.inject.Singleton;
 import org.opentripplanner.routing.graph.Graph;
 import org.opentripplanner.routing.linking.VertexLinker;
 import org.opentripplanner.standalone.config.BuildConfig;
@@ -16,6 +17,7 @@ public class VertexLinkerGraphBuildingModule {
    * The linker doesn't need to be a singleton as all state is kept in the graph.
    */
   @Provides
+  @Singleton
   static VertexLinker linker(Graph graph, BuildConfig config) {
     var mode = VertexLinker.VisibilityMode.ofBoolean(config.areaVisibility);
     return new VertexLinker(graph, mode, config.maxAreaNodes);

application/src/main/java/org/opentripplanner/routing/linking/configure/VertexLinkerRoutingModule.java

@@ -4,6 +4,7 @@
 
 import dagger.Module;
 import dagger.Provides;
+import jakarta.inject.Singleton;
 import org.opentripplanner.routing.graph.Graph;
 import org.opentripplanner.routing.linking.VertexLinker;
 import org.opentripplanner.street.model.StreetLimitationParameters;
@@ -15,6 +16,7 @@
 public class VertexLinkerRoutingModule {
 
   @Provides
+  @Singleton
   static VertexLinker linker(Graph graph, StreetLimitationParameters params) {
     return new VertexLinker(graph, COMPUTE_AREA_VISIBILITY, params.maxAreaNodes());
   }