Return a 404 if there is no opt-out configuration

Author: bernd

src/main/java/org/graylog/plugins/usagestatistics/UsageStatsOptOutResource.java

@@ -29,6 +29,7 @@
 import javax.validation.constraints.NotNull;
 import javax.ws.rs.Consumes;
 import javax.ws.rs.GET;
+import javax.ws.rs.NotFoundException;
 import javax.ws.rs.POST;
 import javax.ws.rs.Path;
 import javax.ws.rs.Produces;
@@ -53,7 +54,13 @@ public UsageStatsOptOutResource(UsageStatsOptOutService usageStatsOptOutService)
             @ApiResponse(code = 500, message = "Internal Server Error")
     })
     public UsageStatsOptOutState getOptOutState() {
-        return usageStatsOptOutService.getOptOutState();
+        final UsageStatsOptOutState optOutState = usageStatsOptOutService.getOptOutState();
+
+        if (optOutState == null) {
+            throw new NotFoundException();
+        }
+
+        return optOutState;
     }
 
     @POST

src/main/java/org/graylog/plugins/usagestatistics/UsageStatsOptOutService.java

@@ -60,8 +60,9 @@ public UsageStatsOptOutService(ClusterConfigService clusterConfigService,
         this.objectMapper = objectMapper;
     }
 
+    @Nullable
     public UsageStatsOptOutState getOptOutState() {
-        return clusterConfigService.getOrDefault(UsageStatsOptOutState.class, UsageStatsOptOutState.create(false));
+        return clusterConfigService.get(UsageStatsOptOutState.class);
     }
 
     public void setOptOutState(final UsageStatsOptOutState optOutState) {

src/test/java/org/graylog/plugins/usagestatistics/UsageStatsOptOutServiceTest.java

@@ -84,7 +84,7 @@ public void tearDown() throws Exception {
     @Test
     public void testGetOptOutState() throws Exception {
         clusterConfigService.clear();
-        assertThat(optOutService.getOptOutState().isOptOut()).isFalse();
+        assertThat(optOutService.getOptOutState()).isNull();
 
         clusterConfigService.write(UsageStatsOptOutState.create(false));
         assertThat(optOutService.getOptOutState().isOptOut()).isFalse();