`gradle check -xforbiddenPatterns` passes!

Hurray! Now we just have to keep it that way!

Original commit: elastic/x-pack-elasticsearch@98b8ede44e

sql/cli/src/main/java/org/elasticsearch/xpack/sql/cli/net/client/HttpClient.java

@@ -7,10 +7,12 @@ package org.elasticsearch.xpack.sql.cli.net.client;
 
 import org.elasticsearch.xpack.sql.cli.CliConfiguration;
 import org.elasticsearch.xpack.sql.net.client.ClientException;
-import org.elasticsearch.xpack.sql.net.client.DataOutputConsumer;
+import org.elasticsearch.xpack.sql.net.client.JreHttpUrlConnection;
-import org.elasticsearch.xpack.sql.net.client.jre.JreHttpUrlConnection;
 import org.elasticsearch.xpack.sql.net.client.util.Bytes;
+import org.elasticsearch.xpack.sql.net.client.util.CheckedConsumer;
 
+import java.io.DataOutput;
+import java.io.IOException;
 import java.net.MalformedURLException;
 import java.net.URL;
 import java.security.AccessController;
@@ -42,11 +44,11 @@ class HttpClient {
         }
     }
 
-    Bytes put(DataOutputConsumer os) {
+    Bytes put(CheckedConsumer<DataOutput, IOException> os) {
         return put("", os);
     }
 
-    Bytes put(String path, DataOutputConsumer os) {
+    Bytes put(String path, CheckedConsumer<DataOutput, IOException> os) {
         try {
             return AccessController.doPrivileged((PrivilegedAction<Bytes>) () -> {
                 return JreHttpUrlConnection.http(url(path), cfg, con -> {

sql/jdbc/src/main/java/org/elasticsearch/xpack/sql/jdbc/net/client/HttpClient.java

@@ -9,9 +9,11 @@ import org.elasticsearch.xpack.sql.jdbc.jdbc.JdbcConfiguration;
 import org.elasticsearch.xpack.sql.jdbc.jdbc.JdbcException;
 import org.elasticsearch.xpack.sql.jdbc.util.BytesArray;
 import org.elasticsearch.xpack.sql.net.client.ClientException;
-import org.elasticsearch.xpack.sql.net.client.DataOutputConsumer;
+import org.elasticsearch.xpack.sql.net.client.JreHttpUrlConnection;
-import org.elasticsearch.xpack.sql.net.client.jre.JreHttpUrlConnection;
+import org.elasticsearch.xpack.sql.net.client.util.CheckedConsumer;
 
+import java.io.DataOutput;
+import java.io.IOException;
 import java.net.MalformedURLException;
 import java.net.URL;
 import java.security.AccessController;
@@ -56,11 +58,11 @@ class HttpClient {
         }
     }
 
-    BytesArray put(DataOutputConsumer os) throws SQLException {
+    BytesArray put(CheckedConsumer<DataOutput, IOException> os) throws SQLException {
         return put("_jdbc?error_trace=true", os); // NOCOMMIT Do something with the error trace. Useful for filing bugs and debugging.
     }
 
-    BytesArray put(String path, DataOutputConsumer os) throws SQLException { // NOCOMMIT remove path?
+    BytesArray put(String path, CheckedConsumer<DataOutput, IOException> os) throws SQLException { // NOCOMMIT remove path?
         try {
             return AccessController.doPrivileged((PrivilegedAction<BytesArray>) () -> {    
                 return JreHttpUrlConnection.http(url(path), cfg, con -> {

sql/jdbc/src/main/java/org/elasticsearch/xpack/sql/jdbc/util/BytesArray.java

@@ -10,6 +10,7 @@ import org.elasticsearch.xpack.sql.net.client.util.StringUtils;
 
 import java.io.IOException;
 import java.io.OutputStream;
+import java.nio.charset.StandardCharsets;
 
 public class BytesArray {
 
@@ -140,7 +141,7 @@ public class BytesArray {
         if (string == null) {
             return;
         }
-        add(string.getBytes(StringUtils.UTF_8));
+        add(string.getBytes(StandardCharsets.UTF_8));
     }
 
     private void checkSize(int newcount) {

sql/net-client/src/main/java/org/elasticsearch/xpack/sql/net/client/DataOutputConsumer.java

@@ -1,23 +0,0 @@
-/*
- * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
- * or more contributor license agreements. Licensed under the Elastic License;
- * you may not use this file except in compliance with the Elastic License.
- */
-package org.elasticsearch.xpack.sql.net.client;
-
-import java.io.DataOutput;
-import java.io.IOException;
-import java.util.function.Consumer;
-
-public interface DataOutputConsumer extends Consumer<DataOutput> {
-
-    default void accept(DataOutput out) {
-        try {
-            acceptThrows(out);
-        } catch (IOException ex) {
-            throw new ClientException(ex, "Cannot write request");
-        }
-    }
-
-    void acceptThrows(DataOutput out) throws IOException;
-}

sql/net-client/src/main/java/org/elasticsearch/xpack/sql/net/client/JreHttpUrlConnection.java

@@ -3,15 +3,14 @@
  * or more contributor license agreements. Licensed under the Elastic License;
  * you may not use this file except in compliance with the Elastic License.
  */
-package org.elasticsearch.xpack.sql.net.client.jre;
+package org.elasticsearch.xpack.sql.net.client;
 
-import org.elasticsearch.xpack.sql.net.client.ClientException;
-import org.elasticsearch.xpack.sql.net.client.ConnectionConfiguration;
-import org.elasticsearch.xpack.sql.net.client.DataOutputConsumer;
 import org.elasticsearch.xpack.sql.net.client.util.Bytes;
+import org.elasticsearch.xpack.sql.net.client.util.CheckedConsumer;
 import org.elasticsearch.xpack.sql.net.client.util.IOUtils;
 
 import java.io.Closeable;
+import java.io.DataOutput;
 import java.io.DataOutputStream;
 import java.io.IOException;
 import java.io.InputStream;
@@ -57,7 +56,7 @@ public class JreHttpUrlConnection implements Closeable {
         }
     }
 
-    public Bytes put(DataOutputConsumer doc) throws ClientException { // NOCOMMIT why is this called put when it is a post?
+    public Bytes put(CheckedConsumer<DataOutput, IOException> doc) throws ClientException { // NOCOMMIT why is this called put when it is a post?
         try {
             con.setRequestMethod("POST");
             con.setDoOutput(true);

sql/net-client/src/main/java/org/elasticsearch/xpack/sql/net/client/util/CheckedConsumer.java

@@ -0,0 +1,17 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License;
+ * you may not use this file except in compliance with the Elastic License.
+ */
+package org.elasticsearch.xpack.sql.net.client.util;
+
+import java.util.function.Consumer;
+
+/**
+ * A {@link Consumer}-like interface which allows throwing checked exceptions.
+ * Elasticsearch has one of these but we don't depend on Elasticsearch.
+ */
+@FunctionalInterface
+public interface CheckedConsumer<T, E extends Exception> {
+    void accept(T t) throws E;
+}

sql/net-client/src/main/java/org/elasticsearch/xpack/sql/net/client/util/StringUtils.java

@@ -5,7 +5,7 @@
  */
 package org.elasticsearch.xpack.sql.net.client.util;
 
-import java.nio.charset.Charset;
+import java.nio.charset.StandardCharsets;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collection;
@@ -15,8 +15,6 @@ import java.util.List;
 import java.util.StringTokenizer;
 
 public abstract class StringUtils {
-
-    public static final Charset UTF_8 = Charset.forName("UTF-8");
     public static final String EMPTY = "";
     public static final String SLASH = "/";
     public static final String PATH_TOP = "..";
@@ -175,11 +173,11 @@ public abstract class StringUtils {
     }
 
     public static String asUTFString(byte[] content, int offset, int length) {
-        return (content == null || length == 0 ? EMPTY : new String(content, offset, length, UTF_8));
+        return (content == null || length == 0 ? EMPTY : new String(content, offset, length, StandardCharsets.UTF_8));
     }
 
     public static byte[] toUTF(String string) {
-        return string.getBytes(UTF_8);
+        return string.getBytes(StandardCharsets.UTF_8);
     }
 
     // Based on "Algorithms on Strings, Trees and Sequences by Dan Gusfield".

sql/net-client/src/test/java/org/elasticsearch/xpack/sql/net/client/util/StringUtilsTests.java

@@ -0,0 +1,19 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License;
+ * you may not use this file except in compliance with the Elastic License.
+ */
+package org.elasticsearch.xpack.sql.net.client.util;
+
+import org.elasticsearch.test.ESTestCase;
+
+import static org.elasticsearch.xpack.sql.net.client.util.StringUtils.nullAsEmpty;
+
+public class StringUtilsTests extends ESTestCase {
+    public void testNullAsEmpty() {
+        assertEquals("", nullAsEmpty(null));
+        assertEquals("", nullAsEmpty(""));
+        String rando = randomRealisticUnicodeOfCodepointLength(5);
+        assertEquals(rando, nullAsEmpty(rando));
+    }
+}