SOLR-18137: Prevent use of Fully Qualified Name in classes (#4165)

Author: epugh

gradle/validation/error-prone.gradle

@@ -540,6 +540,7 @@ allprojects {prj ->
             '-Xep:UnescapedEntity:WARN',
             // '-Xep:UnicodeEscape:OFF', // can't enable since Lucene/Solr tests use unicode a bunch
             // '-Xep:UnnecessaryAssignment:OFF', // we don't use these annotations
+            '-Xep:UnnecessarilyFullyQualified:WARN',
             '-Xep:UnnecessaryAsync:WARN',
             // '-Xep:UnnecessaryBreakInSwitch:WARN', // todo check if useful or comment why not
             // '-Xep:UnnecessaryCopy:OFF', // proto-specific, not widely used
@@ -587,3 +588,21 @@ allprojects {prj ->
     }
   }
 }
+
+// Exclude generated OpenAPI sources in solrj from Error Prone checks.
+configure(project(":solr:solrj")) {
+  plugins.withId(libs.plugins.ltgt.errorprone.get().pluginId) {
+    tasks.withType(JavaCompile) {
+      options.errorprone.excludedPaths = ".*/build/generated/.*"
+    }
+  }
+}
+
+// Exclude JavaCC-generated parser sources in solr:core from Error Prone checks.
+configure(project(":solr:core")) {
+  plugins.withId(libs.plugins.ltgt.errorprone.get().pluginId) {
+    tasks.withType(JavaCompile) {
+      options.errorprone.excludedPaths = ".*/org/apache/solr/parser/.*"
+    }
+  }
+}

solr/core/src/java/org/apache/solr/cli/RunExampleTool.java

@@ -17,6 +17,7 @@
 
 package org.apache.solr.cli;
 
+import java.io.ByteArrayInputStream;
 import java.io.IOException;
 import java.io.InputStream;
 import java.net.Socket;
@@ -560,7 +561,7 @@ protected void runCloudExample(CommandLine cli) throws Exception {
       // Create a scanner from the provided prompts
       String promptsValue = cli.getOptionValue(PROMPT_INPUTS_OPTION);
       InputStream promptsStream =
-          new java.io.ByteArrayInputStream(promptsValue.getBytes(StandardCharsets.UTF_8));
+          new ByteArrayInputStream(promptsValue.getBytes(StandardCharsets.UTF_8));
       readInput = new Scanner(promptsStream, StandardCharsets.UTF_8);
       readInput.useDelimiter(",");
       prompt = true; // Enable prompting code path, but reading from prompts instead of user

solr/core/src/java/org/apache/solr/cli/SolrCLI.java

@@ -25,6 +25,7 @@
 import java.nio.file.Path;
 import java.util.ArrayList;
 import java.util.Arrays;
+import java.util.Collections;
 import java.util.Enumeration;
 import java.util.List;
 import java.util.Locale;
@@ -39,6 +40,7 @@
 import org.apache.commons.cli.Options;
 import org.apache.commons.cli.ParseException;
 import org.apache.commons.cli.help.HelpFormatter;
+import org.apache.commons.cli.help.TableDefinition;
 import org.apache.commons.cli.help.TextHelpAppendable;
 import org.apache.solr.client.solrj.SolrClient;
 import org.apache.solr.client.solrj.request.ContentStreamUpdateRequest;
@@ -316,16 +318,14 @@ public static HelpFormatter getFormatter() {
     TextHelpAppendable helpAppendable =
         new TextHelpAppendable(System.out) {
           @Override
-          public void appendTable(org.apache.commons.cli.help.TableDefinition table)
-              throws IOException {
+          public void appendTable(TableDefinition table) throws IOException {
             if (table == null) {
               return;
             }
             // Create a new TableDefinition with empty headers to suppress the header row
-            java.util.List<String> emptyHeaders =
-                java.util.Collections.nCopies(table.headers().size(), "");
-            org.apache.commons.cli.help.TableDefinition noHeaderTable =
-                org.apache.commons.cli.help.TableDefinition.from(
+            List<String> emptyHeaders = Collections.nCopies(table.headers().size(), "");
+            TableDefinition noHeaderTable =
+                TableDefinition.from(
                     table.caption(), table.columnTextStyles(), emptyHeaders, table.rows());
             super.appendTable(noHeaderTable);
           }

solr/core/src/java/org/apache/solr/cli/ToolRuntime.java

@@ -35,7 +35,7 @@ public abstract class ToolRuntime {
   public void exit(int status) {
     try {
       System.exit(status);
-    } catch (java.lang.SecurityException secExc) {
+    } catch (SecurityException secExc) {
       if (status != 0) throw new RuntimeException("SolrCLI failed to exit with status " + status);
     }
   }

solr/core/src/java/org/apache/solr/cloud/Overseer.java

@@ -68,6 +68,7 @@
 import org.apache.solr.update.UpdateShardHandler;
 import org.apache.zookeeper.CreateMode;
 import org.apache.zookeeper.KeeperException;
+import org.apache.zookeeper.data.Stat;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -461,7 +462,7 @@ private void checkIfIamStillLeader() {
           && (zkController.getCoreContainer().isShutDown() || zkController.isClosed())) {
         return; // shutting down no need to go further
       }
-      org.apache.zookeeper.data.Stat stat = new org.apache.zookeeper.data.Stat();
+      Stat stat = new Stat();
       final String path = OVERSEER_ELECT + "/leader";
       byte[] data;
       try {

solr/core/src/java/org/apache/solr/cloud/api/collections/RoutedAlias.java

@@ -103,7 +103,7 @@ public static RoutedAlias fromProps(String aliasName, Map<String, String> props)
       // multi-dimensional routed alias
       typeStr = typeStr.substring(DIMENSIONAL.length(), typeStr.length() - 1);
       String[] types = typeStr.split(",");
-      java.util.List<String> fields = new ArrayList<>();
+      List<String> fields = new ArrayList<>();
       if (types.length > 2) {
         throw new SolrException(
             BAD_REQUEST,

solr/core/src/java/org/apache/solr/cluster/placement/impl/PlacementPluginAssignStrategy.java

@@ -27,6 +27,7 @@
 import org.apache.solr.client.solrj.cloud.SolrCloudManager;
 import org.apache.solr.cloud.api.collections.Assign;
 import org.apache.solr.cluster.Node;
+import org.apache.solr.cluster.Replica.ReplicaType;
 import org.apache.solr.cluster.placement.BalanceRequest;
 import org.apache.solr.cluster.placement.DeleteCollectionRequest;
 import org.apache.solr.cluster.placement.DeleteReplicasRequest;
@@ -198,8 +199,7 @@ private static List<ReplicaPosition> computeSystemCollectionPositions(
     ArrayList<Node> nodeList = new ArrayList<>(request.getTargetNodes());
     for (String shard : request.getShardNames()) {
       int replicaNumOfShard = 0;
-      for (org.apache.solr.cluster.Replica.ReplicaType replicaType :
-          org.apache.solr.cluster.Replica.ReplicaType.values()) {
+      for (ReplicaType replicaType : ReplicaType.values()) {
         for (int i = 0; i < request.getCountReplicasToCreate(replicaType); i++) {
           Node assignedNode = nodeList.get(replicaNumOfShard++ % nodeList.size());
           replicaPositions.add(

solr/core/src/java/org/apache/solr/cluster/placement/impl/SimpleClusterAbstractionsImpl.java

@@ -34,6 +34,7 @@
 import org.apache.solr.cluster.SolrCollection;
 import org.apache.solr.common.cloud.ClusterState;
 import org.apache.solr.common.cloud.DocCollection;
+import org.apache.solr.common.cloud.Replica.State;
 import org.apache.solr.common.cloud.Slice;
 import org.apache.solr.common.params.CollectionAdminParams;
 import org.apache.solr.common.util.Pair;
@@ -396,7 +397,7 @@ private Replica.ReplicaType translateType(org.apache.solr.common.cloud.Replica.T
       }
     }
 
-    private Replica.ReplicaState translateState(org.apache.solr.common.cloud.Replica.State state) {
+    private Replica.ReplicaState translateState(State state) {
       switch (state) {
         case ACTIVE:
           return Replica.ReplicaState.ACTIVE;

solr/core/src/java/org/apache/solr/core/SolrConfig.java

@@ -77,6 +77,7 @@
 import org.apache.solr.search.CaffeineCache;
 import org.apache.solr.search.QParserPlugin;
 import org.apache.solr.search.SolrCache;
+import org.apache.solr.search.SolrIndexSearcher;
 import org.apache.solr.search.ValueSourceParser;
 import org.apache.solr.search.stats.StatsCache;
 import org.apache.solr.servlet.SolrRequestParsers;
@@ -320,7 +321,7 @@ private SolrConfig(SolrResourceLoader loader, String name, Properties substituta
       dataDir = get("dataDir").txt();
       if (dataDir != null && dataDir.length() == 0) dataDir = null;
 
-      org.apache.solr.search.SolrIndexSearcher.initRegenerators(this);
+      SolrIndexSearcher.initRegenerators(this);
 
       if (get("jmx").exists()) {
         log.warn(

solr/core/src/java/org/apache/solr/handler/admin/ZookeeperInfoHandler.java

@@ -24,6 +24,7 @@
 import java.net.URLEncoder;
 import java.nio.charset.StandardCharsets;
 import java.util.ArrayList;
+import java.util.Collections;
 import java.util.Comparator;
 import java.util.Date;
 import java.util.LinkedHashMap;
@@ -648,7 +649,7 @@ private boolean buildTree(List<Object> treeList, String path) {
 
         try {
           List<String> children = zkClient.getChildren(path, null);
-          java.util.Collections.sort(children);
+          Collections.sort(children);
 
           for (String child : children) {
             String childPath = path + (path.endsWith("/") ? "" : "/") + child;