Revert "HADOOP-17371. Bump Jetty to the latest version 9.4.34. Contributed by Wei-Chiu Chuang. (#2453)"

This reverts commit 66ee0a6df0dc0dd8242018153fd652a3206e73b5.
diff --git a/hadoop-client-modules/hadoop-client-minicluster/pom.xml b/hadoop-client-modules/hadoop-client-minicluster/pom.xml
index 0bedf1d..70a627c 100644
--- a/hadoop-client-modules/hadoop-client-minicluster/pom.xml
+++ b/hadoop-client-modules/hadoop-client-minicluster/pom.xml
@@ -840,18 +840,6 @@
                         <exclude>*/**</exclude>
                       </excludes>
                     </filter>
-                    <filter>
-                      <artifact>org.eclipse.jetty:jetty-util-ajax</artifact>
-                      <excludes>
-                        <exclude>*/**</exclude>
-                      </excludes>
-                    </filter>
-                    <filter>
-                      <artifact>org.eclipse.jetty:jetty-server</artifact>
-                      <excludes>
-                        <exclude>jetty-dir.css</exclude>
-                      </excludes>
-                    </filter>
                   </filters>
 
                   <!-- relocate classes from mssql-jdbc -->
diff --git a/hadoop-common-project/hadoop-auth/pom.xml b/hadoop-common-project/hadoop-auth/pom.xml
index 10e0b9c..4761945 100644
--- a/hadoop-common-project/hadoop-auth/pom.xml
+++ b/hadoop-common-project/hadoop-auth/pom.xml
@@ -193,10 +193,6 @@
       <artifactId>guava</artifactId>
       <scope>test</scope>
     </dependency>
-    <dependency>
-      <groupId>org.eclipse.jetty</groupId>
-      <artifactId>jetty-server</artifactId>
-    </dependency>
   </dependencies>
 
   <build>
diff --git a/hadoop-common-project/hadoop-auth/src/main/java/org/apache/hadoop/security/authentication/server/AuthenticationFilter.java b/hadoop-common-project/hadoop-auth/src/main/java/org/apache/hadoop/security/authentication/server/AuthenticationFilter.java
index 9f40c42..94d11f48 100644
--- a/hadoop-common-project/hadoop-auth/src/main/java/org/apache/hadoop/security/authentication/server/AuthenticationFilter.java
+++ b/hadoop-common-project/hadoop-auth/src/main/java/org/apache/hadoop/security/authentication/server/AuthenticationFilter.java
@@ -19,7 +19,6 @@
 import org.apache.hadoop.security.authentication.client.AuthenticationException;
 import org.apache.hadoop.security.authentication.client.KerberosAuthenticator;
 import org.apache.hadoop.security.authentication.util.*;
-import org.eclipse.jetty.server.Response;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -620,20 +619,11 @@
                 KerberosAuthenticator.WWW_AUTHENTICATE))) {
           errCode = HttpServletResponse.SC_FORBIDDEN;
         }
-        // After Jetty 9.4.21, sendError() no longer allows a custom message.
-        // use setStatusWithReason() to set a custom message.
-        String reason;
         if (authenticationEx == null) {
-          reason = "Authentication required";
+          httpResponse.sendError(errCode, "Authentication required");
         } else {
-          reason = authenticationEx.getMessage();
+          httpResponse.sendError(errCode, authenticationEx.getMessage());
         }
-
-        if (httpResponse instanceof Response) {
-          ((Response)httpResponse).setStatusWithReason(errCode, reason);
-        }
-
-        httpResponse.sendError(errCode, reason);
       }
     }
   }
diff --git a/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/security/http/RestCsrfPreventionFilter.java b/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/security/http/RestCsrfPreventionFilter.java
index b81ed8e..59cb0d6 100644
--- a/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/security/http/RestCsrfPreventionFilter.java
+++ b/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/security/http/RestCsrfPreventionFilter.java
@@ -37,7 +37,6 @@
 import org.apache.hadoop.classification.InterfaceStability;
 import org.apache.hadoop.conf.Configuration;
 
-import org.eclipse.jetty.server.Response;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -272,10 +271,6 @@
 
     @Override
     public void sendError(int code, String message) throws IOException {
-      if (httpResponse instanceof Response) {
-        ((Response)httpResponse).setStatusWithReason(code, message);
-      }
-
       httpResponse.sendError(code, message);
     }
   }
diff --git a/hadoop-common-project/hadoop-kms/src/main/java/org/apache/hadoop/crypto/key/kms/server/KMSAuthenticationFilter.java b/hadoop-common-project/hadoop-kms/src/main/java/org/apache/hadoop/crypto/key/kms/server/KMSAuthenticationFilter.java
index ead22e4..c020af2 100644
--- a/hadoop-common-project/hadoop-kms/src/main/java/org/apache/hadoop/crypto/key/kms/server/KMSAuthenticationFilter.java
+++ b/hadoop-common-project/hadoop-kms/src/main/java/org/apache/hadoop/crypto/key/kms/server/KMSAuthenticationFilter.java
@@ -28,7 +28,6 @@
 import org.apache.hadoop.security.token.delegation.web.DelegationTokenAuthenticationHandler;
 import org.apache.hadoop.security.token.delegation.web.KerberosDelegationTokenAuthenticationHandler;
 import org.apache.hadoop.security.token.delegation.web.PseudoDelegationTokenAuthenticationHandler;
-import org.eclipse.jetty.server.Response;
 
 import javax.servlet.FilterChain;
 import javax.servlet.FilterConfig;
@@ -114,18 +113,6 @@
     public void sendError(int sc, String msg) throws IOException {
       statusCode = sc;
       this.msg = msg;
-
-      ServletResponse response = getResponse();
-
-      // After Jetty 9.4.21, sendError() no longer allows a custom message.
-      // use setStatusWithReason() to set a custom message.
-      if (response instanceof Response) {
-        ((Response) response).setStatusWithReason(sc, msg);
-      } else {
-        KMS.LOG.warn("The wrapped response object is instance of {}" +
-            ", not org.eclipse.jetty.server.Response. Can't set custom error " +
-            "message", response.getClass());
-      }
       super.sendError(sc, HtmlQuoting.quoteHtmlChars(msg));
     }
 
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/ImageServlet.java b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/ImageServlet.java
index 54825d8..54c8738 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/ImageServlet.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/ImageServlet.java
@@ -42,7 +42,6 @@
 import org.apache.hadoop.hdfs.DFSConfigKeys;
 import org.apache.hadoop.hdfs.DFSUtilClient;
 import org.apache.hadoop.security.SecurityUtil;
-import org.eclipse.jetty.server.Response;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 import org.apache.hadoop.classification.InterfaceAudience;
@@ -120,7 +119,7 @@
     if (nnImage == null) {
       String errorMsg = "NameNode initialization not yet complete. "
           + "FSImage has not been set in the NameNode.";
-      sendError(response, HttpServletResponse.SC_FORBIDDEN, errorMsg);
+      response.sendError(HttpServletResponse.SC_FORBIDDEN, errorMsg);
       throw new IOException(errorMsg);
     }
     return nnImage;
@@ -219,7 +218,7 @@
       
     } catch (Throwable t) {
       String errMsg = "GetImage failed. " + StringUtils.stringifyException(t);
-      sendError(response, HttpServletResponse.SC_GONE, errMsg);
+      response.sendError(HttpServletResponse.SC_GONE, errMsg);
       throw new IOException(errMsg);
     } finally {
       response.getOutputStream().close();
@@ -235,7 +234,7 @@
             conf)) {
       String errorMsg = "Only Namenode, Secondary Namenode, and administrators may access "
           + "this servlet";
-      sendError(response, HttpServletResponse.SC_FORBIDDEN, errorMsg);
+      response.sendError(HttpServletResponse.SC_FORBIDDEN, errorMsg);
       LOG.warn("Received non-NN/SNN/administrator request for image or edits from "
           + request.getUserPrincipal().getName()
           + " at "
@@ -248,7 +247,7 @@
         && !myStorageInfoString.equals(theirStorageInfoString)) {
       String errorMsg = "This namenode has storage info " + myStorageInfoString
           + " but the secondary expected " + theirStorageInfoString;
-      sendError(response, HttpServletResponse.SC_FORBIDDEN, errorMsg);
+      response.sendError(HttpServletResponse.SC_FORBIDDEN, errorMsg);
       LOG.warn("Received an invalid request file transfer request "
           + "from a secondary with storage info " + theirStorageInfoString);
       throw new IOException(errorMsg);
@@ -579,7 +578,7 @@
                 // we need a different response type here so the client can differentiate this
                 // from the failure to upload due to (1) security, or (2) other checkpoints already
                 // present
-                sendError(response, HttpServletResponse.SC_EXPECTATION_FAILED,
+                response.sendError(HttpServletResponse.SC_EXPECTATION_FAILED,
                     "Nameode "+request.getLocalAddr()+" is currently not in a state which can "
                         + "accept uploads of new fsimages. State: "+state);
                 return null;
@@ -594,7 +593,7 @@
               // if the node is attempting to upload an older transaction, we ignore it
               SortedSet<ImageUploadRequest> larger = currentlyDownloadingCheckpoints.tailSet(imageRequest);
               if (larger.size() > 0) {
-                sendError(response, HttpServletResponse.SC_CONFLICT,
+                response.sendError(HttpServletResponse.SC_CONFLICT,
                     "Another checkpointer is already in the process of uploading a" +
                         " checkpoint made up to transaction ID " + larger.last());
                 return null;
@@ -602,7 +601,7 @@
 
               //make sure no one else has started uploading one
               if (!currentlyDownloadingCheckpoints.add(imageRequest)) {
-                sendError(response, HttpServletResponse.SC_CONFLICT,
+                response.sendError(HttpServletResponse.SC_CONFLICT,
                     "Either current namenode is checkpointing or another"
                         + " checkpointer is already in the process of "
                         + "uploading a checkpoint made at transaction ID "
@@ -649,7 +648,7 @@
                     (txid - lastCheckpointTxid) + " expecting at least "
                     + checkpointTxnCount;
                 LOG.info(message);
-                sendError(response, HttpServletResponse.SC_CONFLICT, message);
+                response.sendError(HttpServletResponse.SC_CONFLICT, message);
                 return null;
               }
 
@@ -659,7 +658,7 @@
                       + "another checkpointer already uploaded an "
                       + "checkpoint for txid " + txid;
                   LOG.info(message);
-                  sendError(response, HttpServletResponse.SC_CONFLICT, message);
+                  response.sendError(HttpServletResponse.SC_CONFLICT, message);
                   return null;
                 }
 
@@ -696,20 +695,11 @@
           });
     } catch (Throwable t) {
       String errMsg = "PutImage failed. " + StringUtils.stringifyException(t);
-      sendError(response, HttpServletResponse.SC_GONE, errMsg);
+      response.sendError(HttpServletResponse.SC_GONE, errMsg);
       throw new IOException(errMsg);
     }
   }
 
-  private void sendError(HttpServletResponse response, int code, String message)
-      throws IOException {
-    if (response instanceof Response) {
-      ((Response)response).setStatusWithReason(code, message);
-    }
-
-    response.sendError(code, message);
-  }
-
   /*
    * Params required to handle put image request
    */
diff --git a/hadoop-project/pom.xml b/hadoop-project/pom.xml
index 6f644eb..29faab6 100644
--- a/hadoop-project/pom.xml
+++ b/hadoop-project/pom.xml
@@ -37,7 +37,7 @@
     <!--Whether to proceed to next module if any test failures exist-->
     <ignoreTestFailure>true</ignoreTestFailure>
     <maven.test.redirectTestOutputToFile>true</maven.test.redirectTestOutputToFile>
-    <jetty.version>9.4.35.v20201120</jetty.version>
+    <jetty.version>9.4.20.v20190813</jetty.version>
     <test.exclude>_</test.exclude>
     <test.exclude.pattern>_</test.exclude.pattern>