diff --git a/core/src/main/java/hudson/util/LogTaskListener.java b/core/src/main/java/hudson/util/LogTaskListener.java
index 7d696ada4632..267f8f7bf27f 100644
--- a/core/src/main/java/hudson/util/LogTaskListener.java
+++ b/core/src/main/java/hudson/util/LogTaskListener.java
@@ -37,12 +37,10 @@
 import java.util.logging.LogRecord;
 import java.util.logging.Logger;
 
-// TODO: AbstractTaskListener is empty now, but there are dependencies on that e.g. Ruby Runtime - JENKINS-48116)
-// The change needs API deprecation policy or external usages cleanup.
-
 /**
  * {@link TaskListener} which sends messages to a {@link Logger}.
  */
+@SuppressWarnings("deprecation") // to preserve serial form
 public class LogTaskListener extends AbstractTaskListener implements TaskListener, Closeable {
 
     // would be simpler to delegate to the LogOutputStream but this would incompatibly change the serial form
diff --git a/core/src/main/java/hudson/util/StreamTaskListener.java b/core/src/main/java/hudson/util/StreamTaskListener.java
index 8aad40f5b599..f19db94b45cd 100644
--- a/core/src/main/java/hudson/util/StreamTaskListener.java
+++ b/core/src/main/java/hudson/util/StreamTaskListener.java
@@ -48,9 +48,6 @@
 import jenkins.util.SystemProperties;
 import org.kohsuke.stapler.framework.io.WriterOutputStream;
 
-// TODO: AbstractTaskListener is empty now, but there are dependencies on that e.g. Ruby Runtime - JENKINS-48116)
-// The change needs API deprecation policy or external usages cleanup.
-
 /**
  * {@link TaskListener} that generates output into a single stream.
  *
@@ -59,6 +56,7 @@
  *
  * @author Kohsuke Kawaguchi
  */
+@SuppressWarnings("deprecation") // to preserve serial form
 public class StreamTaskListener extends AbstractTaskListener implements TaskListener, Closeable {
     @NonNull
     private PrintStream out;
diff --git a/core/src/main/resources/hudson/model/Api/index.jelly b/core/src/main/resources/hudson/model/Api/index.jelly
index b927eafb513d..cc208c986d7d 100644
--- a/core/src/main/resources/hudson/model/Api/index.jelly
+++ b/core/src/main/resources/hudson/model/Api/index.jelly
@@ -84,18 +84,6 @@ THE SOFTWARE.
            <code>ast.literal_eval(urllib.urlopen("...").read())</code>
          </p>
         </dd>
-
-        <!--
-        <dt><a href="ruby?pretty=true">Ruby API</a></dt>
-        <dd>
-         <p>
-           Access the same data as Ruby literals that can be <code>eval</code>ed.
-
-           However, when you do this, beware of the security implication. If you are connecting
-           to a non-trusted Jenkins, the server can send you malicious Python programs.
-         </p>
-        </dd>
-        -->
       </dl>
 
       <p>
diff --git a/test/src/test/java/hudson/util/LogTaskListenerTest.java b/test/src/test/java/hudson/util/LogTaskListenerTest.java
index 72b89f64a205..f1dad026f5d6 100644
--- a/test/src/test/java/hudson/util/LogTaskListenerTest.java
+++ b/test/src/test/java/hudson/util/LogTaskListenerTest.java
@@ -30,6 +30,7 @@
 import hudson.model.TaskListener;
 import java.util.logging.Level;
 import java.util.logging.Logger;
+import jenkins.security.MasterToSlaveCallable;
 import org.junit.Rule;
 import org.junit.Test;
 import org.jvnet.hudson.test.JenkinsRule;
@@ -56,4 +57,28 @@ public void annotations() throws Exception {
         assertEquals("[plain line, from annotate, from hyperlink, there from encoded]", logging.getMessages().toString());
     }
 
+    @Test
+    public void serialization() throws Exception {
+        TaskListener l = new LogTaskListener(Logger.getLogger("LogTaskListenerTest"), Level.INFO);
+        r.createOnlineSlave().getChannel().call(new Log(l));
+        assertEquals("[from agent]", logging.getMessages().toString());
+    }
+
+    private static final class Log extends MasterToSlaveCallable<Void, RuntimeException> {
+
+        private final TaskListener l;
+
+        Log(TaskListener l) {
+            this.l = l;
+        }
+
+        @Override
+        public Void call() throws RuntimeException {
+            l.getLogger().println("from agent");
+            l.getLogger().flush();
+            return null;
+        }
+
+    }
+
 }