InjectedValue impl that exposes an Optional.

clustering/service/src/main/java/org/wildfly/clustering/service/OptionalInjectedValue.java

@@ -0,0 +1,53 @@
+/*
+ * JBoss, Home of Professional Open Source.
+ * Copyright 2017, Red Hat, Inc., and individual contributors
+ * as indicated by the @author tags. See the copyright.txt file in the
+ * distribution for a full listing of individual contributors.
+ *
+ * This is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU Lesser General Public License as
+ * published by the Free Software Foundation; either version 2.1 of
+ * the License, or (at your option) any later version.
+ *
+ * This software is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this software; if not, write to the Free
+ * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
+ * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
+ */
+
+package org.wildfly.clustering.service;
+
+import java.util.Optional;
+
+import org.jboss.msc.inject.RetainingInjector;
+import org.jboss.msc.value.Value;
+
+/**
+ * Like {@link org.jboss.msc.value.InjectedValue}, but with support for returning an {@link Optional}.
+ * @author Paul Ferraro
+ */
+public class OptionalInjectedValue<T> extends RetainingInjector<T> implements Value<T> {
+
+    @Override
+    public T getValue() {
+        Value<T> value = getStoredValue();
+        if (value == null) {
+            throw new IllegalStateException();
+        }
+        return value.getValue();
+    }
+
+    /**
+     * Returns the optional value, which is only defined if a value was injected.
+     * Analogous to {@link org.jboss.msc.value.InjectedValue#getOptionalValue()}.
+     * @return an optional injected value
+     */
+    public Optional<T> getOptionalValue() {
+        return Optional.ofNullable(this.getStoredValue()).map(Value::getValue);
+    }
+}