feat(graphql): add top-level query for targetNodes

src/main/java/io/cryostat/ObjectMapperCustomization.java

@@ -0,0 +1,83 @@
+/*
+ * Copyright The Cryostat Authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package io.cryostat;
+
+import java.io.IOException;
+import java.util.Map;
+
+import com.fasterxml.jackson.core.JsonGenerator;
+import com.fasterxml.jackson.core.Version;
+import com.fasterxml.jackson.databind.BeanDescription;
+import com.fasterxml.jackson.databind.JsonSerializer;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.fasterxml.jackson.databind.SerializationConfig;
+import com.fasterxml.jackson.databind.SerializerProvider;
+import com.fasterxml.jackson.databind.module.SimpleModule;
+import com.fasterxml.jackson.databind.ser.BeanSerializerModifier;
+import com.fasterxml.jackson.databind.type.MapType;
+import io.quarkus.jackson.ObjectMapperCustomizer;
+import jakarta.inject.Singleton;
+
+@Singleton
+public class ObjectMapperCustomization implements ObjectMapperCustomizer {
+
+    @Override
+    public void customize(ObjectMapper objectMapper) {
+        // FIXME get this version information from the maven build somehow
+        SimpleModule mapModule =
+                new SimpleModule(
+                        "MapSerialization", new Version(3, 0, 0, null, "io.cryostat", "cryostat"));
+
+        mapModule.setSerializerModifier(new MapSerializerModifier());
+
+        objectMapper.registerModule(mapModule);
+    }
+
+    static class MapSerializerModifier extends BeanSerializerModifier {
+        @Override
+        public JsonSerializer<?> modifyMapSerializer(
+                SerializationConfig config,
+                MapType valueType,
+                BeanDescription beanDesc,
+                JsonSerializer serializer) {
+            if (valueType.getKeyType().getRawClass().equals(String.class)
+                    && valueType.getContentType().getRawClass().equals(String.class)) {
+                return new MapSerializer();
+            }
+            return serializer;
+        }
+    }
+
+    static class MapSerializer extends JsonSerializer<Map<?, ?>> {
+
+        @Override
+        public void serialize(Map<?, ?> map, JsonGenerator gen, SerializerProvider serializers)
+                throws IOException {
+            gen.writeStartArray();
+
+            for (var entry : map.entrySet()) {
+                gen.writeStartObject();
+
+                gen.writePOJOField("key", entry.getKey());
+                gen.writePOJOField("value", entry.getValue());
+
+                gen.writeEndObject();
+            }
+
+            gen.writeEndArray();
+        }
+    }
+}

src/main/java/io/cryostat/graphql/RootNode.java

@@ -24,6 +24,7 @@
 import io.cryostat.discovery.DiscoveryNode;
 import io.cryostat.graphql.matchers.LabelSelectorMatcher;
 
+import edu.umd.cs.findbugs.annotations.SuppressFBWarnings;
 import io.smallrye.graphql.api.Nullable;
 import org.eclipse.microprofile.graphql.Description;
 import org.eclipse.microprofile.graphql.GraphQLApi;
@@ -43,7 +44,7 @@ public DiscoveryNode getRootNode() {
             "Get target nodes that are descendants of this node. That is, get the set of leaf nodes"
                     + " from anywhere below this node's subtree.")
     public List<DiscoveryNode> descendantTargets(
-            @Source DiscoveryNode discoveryNode, DescendantTargetsFilterInput filter) {
+            @Source DiscoveryNode discoveryNode, DiscoveryNodeFilter filter) {
         // TODO do this filtering at the database query level as much as possible. As is, this will
         // load the entire discovery tree out of the database, then perform the filtering at the
         // application level.
@@ -64,7 +65,8 @@ private Set<DiscoveryNode> recurseChildren(
         return result;
     }
 
-    public static class DescendantTargetsFilterInput implements Predicate<DiscoveryNode> {
+    @SuppressFBWarnings(value = "URF_UNREAD_PUBLIC_OR_PROTECTED_FIELD")
+    public static class DiscoveryNodeFilter implements Predicate<DiscoveryNode> {
         public @Nullable Long id;
         public @Nullable String name;
         public @Nullable List<String> names;