Suppress an idle timeout from Jetty which would otherwise interfere with interactive commands.

cli/src/main/java/hudson/cli/PlainCLIProtocol.java

@@ -34,6 +34,7 @@ import java.io.InputStream;
 import java.io.OutputStream;
 import java.nio.channels.ClosedChannelException;
 import java.nio.channels.ReadPendingException;
+import java.util.concurrent.TimeoutException;
 import java.util.logging.Level;
 import java.util.logging.Logger;
 import org.apache.commons.io.IOUtils;
@@ -106,6 +107,13 @@ class PlainCLIProtocol {
                         } catch (EOFException x) {
                             handleClose();
                             break; // TODO verify that we hit EOF immediately, not partway into framelen
+                        } catch (IOException x) {
+                            if (x.getCause() instanceof TimeoutException) {
+                                LOGGER.log(Level.FINE, "ignoring idle timeout, perhaps from Jetty", x);
+                                continue;
+                            } else {
+                                throw x;
+                            }
                         }
                         if (framelen < 0) {
                             throw new IOException("corrupt stream: negative frame length");

test/src/test/java/hudson/cli/CLIActionTest.java

@@ -257,6 +257,7 @@ public class CLIActionTest {
     @Issue("JENKINS-41745")
     @Test
     public void interleavedStdio() throws Exception {
+        logging.record(PlainCLIProtocol.class, Level.FINE);
         File jar = tmp.newFile("jenkins-cli.jar");
         FileUtils.copyURLToFile(j.jenkins.getJnlpJars("jenkins-cli.jar").getURL(), jar);
         ByteArrayOutputStream baos = new ByteArrayOutputStream();
@@ -273,6 +274,7 @@ public class CLIActionTest {
         while (!baos.toString().contains("121")) { // ditto not "===> 121"
             Thread.sleep(100);
         }
+        Thread.sleep(31_000); // aggravate org.eclipse.jetty.io.IdleTimeout (cf. AbstractConnector._idleTimeout)
         pw.println("11 * 11 * 11");
         while (!baos.toString().contains("1331")) {
             Thread.sleep(100);