Introduces an ExecutorServices implementation to Helidon's repackaged…

… Weld implementation to ensure context classloaders are never null (#2269)

* Introduces an ExecutorServices implementation to Helidon's repackaged Weld implementation to ensure context classloaders are never null.
Signed-off-by: Laird Nelson <laird.nelson@oracle.com>

microprofile/cdi/src/main/java/io/helidon/microprofile/cdi/ExecutorServices.java

@@ -0,0 +1,63 @@
+/*
+ * Copyright (c) 2020 Oracle and/or its affiliates.
+ *
+ * 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.helidon.microprofile.cdi;
+
+import java.util.Collection;
+import java.util.concurrent.Callable;
+
+import org.jboss.weld.executor.CommonForkJoinPoolExecutorServices;
+
+/**
+ * A {@link CommonForkJoinPoolExecutorServices} whose {@link
+ * #wrap(Collection)} method simply returns the supplied {@link
+ * Collection} of {@link Callable}s unchanged.
+ *
+ * <p>This class exists to work around <a
+ * href="https://issues.redhat.com/browse/WELD-2494"
+ * target="_parent">WELD-2494</a>, which, in turn, was working around
+ * <a href="https://bugs.openjdk.java.net/browse/JDK-8184335"
+ * target="_parent">JDK-8184335</a>.</p>
+ *
+ * @see #wrap(Collection)
+ */
+public final class ExecutorServices extends CommonForkJoinPoolExecutorServices {
+
+    /**
+     * Creates a new {@link ExecutorServices}.
+     *
+     * <p>There is no reason for users to call this constructor.</p>
+     */
+    public ExecutorServices() {
+        super();
+    }
+
+    /**
+     * Returns the supplied {@code tasks} argument unchanged when invoked.
+     *
+     * @param tasks a {@link Collection} of {@link Callable}s
+     * representing tasks that Weld needs to do; may be {@code null}
+     *
+     * @return the supplied {@code tasks} argument
+     *
+     * @see <a href="https://issues.redhat.com/browse/WELD-2494"
+     * target="_parent">WELD-2494</a>
+     */
+    @Override
+    public <T> Collection<? extends Callable<T>> wrap(Collection<? extends Callable<T>> tasks) {
+        return tasks;
+    }
+
+}

microprofile/cdi/src/main/java/module-info.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2019, 2020 Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2019, 2020 Oracle and/or its affiliates.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -16,6 +16,7 @@
 
 import javax.enterprise.inject.se.SeContainerInitializer;
 
+import io.helidon.microprofile.cdi.ExecutorServices;
 import io.helidon.microprofile.cdi.HelidonContainerInitializer;
 
 /**
@@ -44,4 +45,5 @@
     uses javax.enterprise.inject.spi.Extension;
 
     provides SeContainerInitializer with HelidonContainerInitializer;
+    provides org.jboss.weld.bootstrap.api.Service with ExecutorServices;
 }

microprofile/cdi/src/main/resources/META-INF/services/org.jboss.weld.bootstrap.api.Service

@@ -0,0 +1,17 @@
+#
+# Copyright (c) 2020 Oracle and/or its affiliates.
+#
+# 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.
+#
+
+io.helidon.microprofile.weld.ExecutorServices