Make workflow-api compatible with Guava 21.0 and newer

.mvn/extensions.xml

@@ -2,6 +2,6 @@
   <extension>
     <groupId>io.jenkins.tools.incrementals</groupId>
     <artifactId>git-changelist-maven-extension</artifactId>
-    <version>1.0-beta-4</version>
+    <version>1.2</version>
   </extension>
 </extensions>

pom.xml

@@ -44,9 +44,9 @@
         </license>
     </licenses>
     <scm>
-        <connection>scm:git:git://github.com/jenkinsci/${project.artifactId}-plugin.git</connection>
-        <developerConnection>scm:git:[email protected]:jenkinsci/${project.artifactId}-plugin.git</developerConnection>
-        <url>https://github.com/jenkinsci/${project.artifactId}-plugin</url>
+        <connection>scm:git:git://github.com/${gitHubRepo}.git</connection>
+        <developerConnection>scm:git:[email protected]:${gitHubRepo}.git</developerConnection>
+        <url>https://github.com/${gitHubRepo}</url>
         <tag>${scmTag}</tag>
     </scm>
     <repositories>
@@ -64,17 +64,18 @@
     <properties>
         <revision>2.42</revision>
         <changelist>-SNAPSHOT</changelist>
-        <jenkins.version>2.176.4</jenkins.version>
+        <jenkins.version>2.222.4</jenkins.version>
         <java.level>8</java.level>
         <no-test-jar>false</no-test-jar>
         <useBeta>true</useBeta>
+        <gitHubRepo>jenkinsci/${project.artifactId}-plugin</gitHubRepo>
     </properties>
     <dependencyManagement>
         <dependencies>
             <dependency>
                 <groupId>io.jenkins.tools.bom</groupId>
-                <artifactId>bom-2.176.x</artifactId>
-                <version>16</version>
+                <artifactId>bom-2.222.x</artifactId>
+                <version>25</version>
                 <scope>import</scope>
                 <type>pom</type>
             </dependency>

src/main/java/org/jenkinsci/plugins/workflow/flow/FlowExecutionList.java

@@ -5,6 +5,7 @@
 import com.google.common.util.concurrent.FutureCallback;
 import com.google.common.util.concurrent.Futures;
 import com.google.common.util.concurrent.ListenableFuture;
+import com.google.common.util.concurrent.MoreExecutors;
 import com.google.inject.Inject;
 import hudson.Extension;
 import hudson.ExtensionList;
@@ -20,10 +21,13 @@
 
 import java.io.File;
 import java.io.IOException;
+import java.lang.reflect.InvocationTargetException;
+import java.lang.reflect.Method;
 import java.util.ArrayList;
 import java.util.Iterator;
 import java.util.List;
 import java.util.concurrent.CancellationException;
+import java.util.concurrent.ExecutorService;
 import java.util.concurrent.RejectedExecutionException;
 import java.util.concurrent.TimeUnit;
 import java.util.logging.Level;
@@ -194,7 +198,7 @@ public void onFailure(Throwable t) {
                             LOGGER.log(WARNING, "Failed to load " + e, t);
                         }
                     }
-                });
+                }, newExecutorService());
             }
         }
     }
@@ -230,7 +234,7 @@ public void onSuccess(List<StepExecution> result) {
                     public void onFailure(Throwable t) {
                         LOGGER.log(Level.WARNING, null, t);
                     }
-                });
+                }, newExecutorService());
             }
 
             return Futures.allAsList(all);
@@ -254,4 +258,25 @@ public void onFailure(Throwable t) {
         executor.awaitTermination(1, TimeUnit.MINUTES);
     }
 
+    /**
+     * Returns an {@link ExecutorService} to be used as a parameter in other methods.
+     * It calls {@code MoreExecutors#sameThreadExecutor} or falls back to {@code MoreExecutors#newDirectExecutorService}
+     * for compatibility with newer (> 18.0) versions of guava.
+     */
+    private static ExecutorService newExecutorService() {
+        try {
+            try {
+                // guava older than 18
+                Method method = MoreExecutors.class.getMethod("sameThreadExecutor");
+                return (ExecutorService) method.invoke(null);
+            } catch (NoSuchMethodException e) {
+                // TODO invert this to prefer the newer guava method once guava is upgraded in Jenkins core
+                Method method = MoreExecutors.class.getMethod("newDirectExecutorService");
+                return (ExecutorService) method.invoke(null);
+            }
+        } catch (IllegalAccessException | InvocationTargetException | NoSuchMethodException e ) {
+            throw new RuntimeException(e);
+        }
+    }
+
 }