SOLR-11261, SOLR-10966: Upgrade to Hadoop 2.7.4 to fix incompatibility with Java 9.

This also reverts commit 85a27a231f.

lucene/ivy-versions.properties

@@ -136,7 +136,7 @@ org.apache.directory.server.version = 2.0.0-M15
 /org.apache.directory.server/apacheds-protocol-shared = ${org.apache.directory.server.version}
 /org.apache.directory.server/apacheds-xdbm-partition = ${org.apache.directory.server.version}
 
-org.apache.hadoop.version = 2.7.2
+org.apache.hadoop.version = 2.7.4
 /org.apache.hadoop/hadoop-annotations = ${org.apache.hadoop.version}
 /org.apache.hadoop/hadoop-auth = ${org.apache.hadoop.version}
 /org.apache.hadoop/hadoop-common = ${org.apache.hadoop.version}

solr/CHANGES.txt

@@ -863,7 +863,7 @@ Other Changes
   with point fields and provides control over dynamic fields used for the raw amount and currency
   code sub-fields.  (hossman, Steve Rowe)
 
-* SOLR-10966: Add workaround for Hadoop-Common 2.7.2 incompatibility with Java 9.
+* SOLR-11261, SOLR-10966: Upgrade to Hadoop 2.7.4 to fix incompatibility with Java 9.
   (Uwe Schindler)
 
 ==================  6.6.1 ==================

solr/core/src/java/org/apache/solr/servlet/BaseSolrFilter.java

@@ -18,8 +18,6 @@ package org.apache.solr.servlet;
 
 import javax.servlet.Filter;
 
-import org.apache.solr.util.Java9InitHack;
-
 /**
  * All Solr filters available to the user's webapp should
  * extend this class and not just implement {@link Filter}.
@@ -30,7 +28,6 @@ abstract class BaseSolrFilter implements Filter {
   
   static {
     CheckLoggingConfiguration.check();
-    Java9InitHack.initJava9();
   }
   
 }

solr/core/src/java/org/apache/solr/servlet/BaseSolrServlet.java

@@ -18,8 +18,6 @@ package org.apache.solr.servlet;
 
 import javax.servlet.http.HttpServlet;
 
-import org.apache.solr.util.Java9InitHack;
-
 /**
  * All Solr servlets available to the user's webapp should
  * extend this class and not {@link HttpServlet}.
@@ -31,7 +29,6 @@ abstract class BaseSolrServlet extends HttpServlet {
   
   static {
     CheckLoggingConfiguration.check();
-    Java9InitHack.initJava9();
   }
   
 }

solr/core/src/java/org/apache/solr/util/Java9InitHack.java

@@ -1,78 +0,0 @@
-/*
- * Licensed to the Apache Software Foundation (ASF) under one or more
- * contributor license agreements.  See the NOTICE file distributed with
- * this work for additional information regarding copyright ownership.
- * The ASF licenses this file to You under the Apache License, Version 2.0
- * (the "License"); you may not use this file except in compliance with
- * the License.  You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-package org.apache.solr.util;
-
-import java.lang.invoke.MethodHandles;
-import java.security.AccessController;
-import java.security.PrivilegedAction;
-import java.util.Objects;
-
-import org.apache.lucene.util.Constants;
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
-
-/**
- * This class works around a bug in hadoop-common-2.7.2 where the Hadoop Shell class cannot
- * initialize on Java 9 (due to a bug while parsing Java's version number).
- * This class does some early checks and fakes the java version for a very short time
- * during class loading of Solr's web application or Solr's test framework.
- * <p>
- * Be sure to run this only in static initializers, as soon as possible after JVM startup!
- * <p>
- * Related issues: HADOOP-14586, SOLR-10966
- * <p>
- * TODO: <b>Remove this ASAP, once we have upgraded Hadoop (SOLR-10951)!</b>
- * 
- * @lucene.internal
- */
-public final class Java9InitHack {
-  private static final Logger log = LoggerFactory.getLogger(MethodHandles.lookup().lookupClass());
-  
-  private static final String JAVA_VERSION_PROP = "java.version";
-  private static boolean done = false;
-
-  /**
-   * Runs the hack. Should be done as early as possible on JVM startup, from a static initializer
-   * to prevent concurrency issues - because we change temporarily some 'important' system properties.
-   */
-  public static synchronized void initJava9() {
-    if (Constants.JRE_IS_MINIMUM_JAVA9 && done == false) {
-      AccessController.doPrivileged((PrivilegedAction<Void>) Java9InitHack::initPrivileged);
-      done = true;
-    }
-  }
-     
-  private static Void initPrivileged() {
-    log.info("Adding temporary workaround for Hadoop's Shell class to allow running on Java 9 (please ignore any warnings/failures).");
-    String oldVersion = System.getProperty(JAVA_VERSION_PROP);
-    try {
-      System.setProperty(JAVA_VERSION_PROP, "1.9");
-      Class.forName("org.apache.hadoop.util.Shell");
-    } catch (Throwable t) {
-      log.warn("Cannot initialize Hadoop's Shell class on Java 9.", t);
-    } finally {
-      if (!Objects.equals(System.getProperty(JAVA_VERSION_PROP), oldVersion)) {
-        System.setProperty(JAVA_VERSION_PROP, oldVersion);
-      }
-    }
-    return null;
-  }
-  
-  private Java9InitHack() {}
-    
-}

solr/licenses/hadoop-annotations-2.7.2.jar.sha1

@@ -1 +0,0 @@
-80693ef2884927ee3c5464a7539fcfa4af382e14

solr/licenses/hadoop-annotations-2.7.4.jar.sha1

@@ -0,0 +1 @@
+d8e0a3abcc3fb46e1418b99d6d1328a95d9bd7b1

solr/licenses/hadoop-auth-2.7.2.jar.sha1

@@ -1 +0,0 @@
-bf613cfec06a1f3d3a91d7f82f9e4af75bc01f72

solr/licenses/hadoop-auth-2.7.4.jar.sha1

@@ -0,0 +1 @@
+a2d5d89a6acfb11dd1a125e86b84fcef549483ae

solr/licenses/hadoop-common-2.7.2-tests.jar.sha1

@@ -1 +0,0 @@
-482b3051dc384c1e15182a6ad1402649ef24be02

solr/licenses/hadoop-common-2.7.2.jar.sha1

@@ -1 +0,0 @@
-422eb48913fa6f81835b3192c97a576505b6c192

solr/licenses/hadoop-common-2.7.4-tests.jar.sha1

@@ -0,0 +1 @@
+a2aa0905c8f980d36f4e861283dccfcad6dd3dec

solr/licenses/hadoop-common-2.7.4.jar.sha1

@@ -0,0 +1 @@
+9afa8d2004a0bbd930d1ac10d221d927917067be

solr/licenses/hadoop-hdfs-2.7.2-tests.jar.sha1

@@ -1 +0,0 @@
-dfb6840b97211044e87a0345f7edad51b942fd2a

solr/licenses/hadoop-hdfs-2.7.2.jar.sha1

@@ -1 +0,0 @@
-3c304b3d9227fbf8af8bc1cab013271538c3cf0a

solr/licenses/hadoop-hdfs-2.7.4-tests.jar.sha1

@@ -0,0 +1 @@
+3e5dbc6eb1d4d5d4c19a06c0a443f5bdc3740a35

solr/licenses/hadoop-hdfs-2.7.4.jar.sha1

@@ -0,0 +1 @@
+3e1414e3ae47e97f66b2eb904d3ec6c50a3e29d0

solr/licenses/hadoop-minikdc-2.7.2.jar.sha1

@@ -1 +0,0 @@
-59d112c8683f563f7aaf05fde7bc4022b90b44a7

solr/licenses/hadoop-minikdc-2.7.4.jar.sha1

@@ -0,0 +1 @@
+3964a7984a19e553e090a2279569ec0060b87d5b

solr/test-framework/src/java/org/apache/solr/SolrTestCaseJ4.java

@@ -116,7 +116,6 @@ import org.apache.solr.schema.SchemaField;
 import org.apache.solr.search.SolrIndexSearcher;
 import org.apache.solr.servlet.DirectSolrConnection;
 import org.apache.solr.util.AbstractSolrTestCase;
-import org.apache.solr.util.Java9InitHack;
 import org.apache.solr.util.LogLevel;
 import org.apache.solr.util.RandomizeSSL;
 import org.apache.solr.util.RandomizeSSL.SSLRandomizer;
@@ -163,11 +162,6 @@ public abstract class SolrTestCaseJ4 extends LuceneTestCase {
 
   private static final Logger log = LoggerFactory.getLogger(MethodHandles.lookup().lookupClass());
 
-  // this must be a static init block to be safe!
-  static {
-    Java9InitHack.initJava9();
-  }
-
   private static final List<String> DEFAULT_STACK_FILTERS = Arrays.asList(new String [] {
       "org.junit.",
       "junit.framework.",