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

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

@@ -43,7 +43,7 @@ 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, DiscoveryNodeFilterInput 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 +64,7 @@ private Set<DiscoveryNode> recurseChildren(
         return result;
     }
 
-    public static class DescendantTargetsFilterInput implements Predicate<DiscoveryNode> {
+    public static class DiscoveryNodeFilterInput implements Predicate<DiscoveryNode> {
         public @Nullable Long id;
         public @Nullable String name;
         public @Nullable List<String> names;

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

@@ -0,0 +1,42 @@
+/*
+ * 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.graphql;
+
+import java.util.List;
+
+import io.cryostat.discovery.DiscoveryNode;
+import io.cryostat.graphql.RootNode.DiscoveryNodeFilterInput;
+import io.cryostat.targets.Target;
+
+import org.eclipse.microprofile.graphql.Description;
+import org.eclipse.microprofile.graphql.GraphQLApi;
+import org.eclipse.microprofile.graphql.Query;
+
+@GraphQLApi
+public class TargetNodes {
+
+    @Query("targetNodes")
+    @Description("Get the Target discovery nodes, i.e. the leaf nodes of the discovery tree")
+    public List<DiscoveryNode> getTargetNodes(DiscoveryNodeFilterInput 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.
+        return Target.<Target>findAll().stream()
+                .map(t -> t.discoveryNode)
+                .filter(n -> filter == null ? true : filter.test(n))
+                .toList();
+    }
+}