Treat path object as a simple value objects instead of Iterable in XContentBuilder, using toString() to create String representation.

This addresses #11771

core/src/main/java/org/elasticsearch/common/xcontent/XContentBuilder.java

@@ -20,6 +20,7 @@
 package org.elasticsearch.common.xcontent;
 
 import com.google.common.base.Charsets;
+
 import org.apache.lucene.util.BytesRef;
 import org.elasticsearch.common.Strings;
 import org.elasticsearch.common.bytes.BytesArray;
@@ -41,6 +42,7 @@ import java.io.InputStream;
 import java.io.OutputStream;
 import java.math.BigDecimal;
 import java.math.RoundingMode;
+import java.nio.file.Path;
 import java.util.Calendar;
 import java.util.Date;
 import java.util.Locale;
@@ -650,21 +652,33 @@ public final class XContentBuilder implements BytesStream, Releasable {
         return this;
     }
 
-    public XContentBuilder field(String name, Iterable value) throws IOException {
+    public XContentBuilder field(String name, Iterable<?> value) throws IOException {
+        if (value instanceof Path) {
+            //treat Paths as single value
+            field(name);
+            value(value);
+        } else {
             startArray(name);
             for (Object o : value) {
                 value(o);
             }
             endArray();
+        }
         return this;
     }
 
-    public XContentBuilder field(XContentBuilderString name, Iterable value) throws IOException {
+    public XContentBuilder field(XContentBuilderString name, Iterable<?> value) throws IOException {
+        if (value instanceof Path) {
+            //treat Paths as single value
+            field(name);
+            value(value);
+        } else {
             startArray(name);
             for (Object o : value) {
                 value(o);
             }
             endArray();
+        }
         return this;
     }
 
@@ -1140,15 +1154,20 @@ public final class XContentBuilder implements BytesStream, Releasable {
         return this;
     }
 
-    public XContentBuilder value(Iterable value) throws IOException {
+    public XContentBuilder value(Iterable<?> value) throws IOException {
         if (value == null) {
             return nullValue();
         }
+        if (value instanceof Path) {
+            //treat as single value
+            writeValue(value);
+        } else {
             startArray();
             for (Object o : value) {
                 value(o);
             }
             endArray();
+        }
         return this;
     }
 
@@ -1231,7 +1250,7 @@ public final class XContentBuilder implements BytesStream, Releasable {
             generator.writeNull();
             return;
         }
-        Class type = value.getClass();
+        Class<?> type = value.getClass();
         if (type == String.class) {
             generator.writeString((String) value);
         } else if (type == Integer.class) {
@@ -1255,9 +1274,12 @@ public final class XContentBuilder implements BytesStream, Releasable {
             generator.writeEndObject();
         } else if (value instanceof Map) {
             writeMap((Map) value);
+        } else if (value instanceof Path) {
+            //Path implements Iterable<Path> and causes endless recursion and a StackOverFlow if treated as an Iterable here
+            generator.writeString(value.toString());
         } else if (value instanceof Iterable) {
             generator.writeStartArray();
-            for (Object v : (Iterable) value) {
+            for (Object v : (Iterable<?>) value) {
                 writeValue(v);
             }
             generator.writeEndArray();

core/src/test/java/org/elasticsearch/common/xcontent/builder/XContentBuilderTests.java

@@ -20,14 +20,17 @@
 package org.elasticsearch.common.xcontent.builder;
 
 import com.google.common.collect.Lists;
+
 import org.elasticsearch.common.bytes.BytesArray;
 import org.elasticsearch.common.io.FastCharArrayWriter;
+import org.elasticsearch.common.io.PathUtils;
 import org.elasticsearch.common.io.stream.BytesStreamOutput;
 import org.elasticsearch.common.xcontent.*;
 import org.elasticsearch.test.ElasticsearchTestCase;
 import org.junit.Test;
 
 import java.io.IOException;
+import java.nio.file.Path;
 import java.util.*;
 
 import static org.elasticsearch.common.xcontent.XContentBuilder.FieldCaseConversion.CAMELCASE;
@@ -260,4 +263,60 @@ public class XContentBuilderTests extends ElasticsearchTestCase {
 
         assertThat(i, equalTo(terms.size()));
     }
+
+    @Test
+    public void testHandlingOfPath() throws IOException {
+        Path path = PathUtils.get("path");
+        checkPathSerialization(path);
+    }
+
+    @Test
+    public void testHandlingOfPath_relative() throws IOException {
+        Path path = PathUtils.get("..", "..", "path");
+        checkPathSerialization(path);
+    }
+
+    @Test
+    public void testHandlingOfPath_absolute() throws IOException {
+        Path path = createTempDir().toAbsolutePath();
+        checkPathSerialization(path);
+    }
+
+    private void checkPathSerialization(Path path) throws IOException {
+        XContentBuilder pathBuilder = XContentFactory.contentBuilder(XContentType.JSON);
+        pathBuilder.startObject().field("file", path).endObject();
+
+        XContentBuilder stringBuilder = XContentFactory.contentBuilder(XContentType.JSON);
+        stringBuilder.startObject().field("file", path.toString()).endObject();
+
+        assertThat(pathBuilder.string(), equalTo(stringBuilder.string()));
+    }
+
+    @Test
+    public void testHandlingOfPath_XContentBuilderStringName() throws IOException {
+        Path path = PathUtils.get("path");
+        XContentBuilderString name = new XContentBuilderString("file");
+
+        XContentBuilder pathBuilder = XContentFactory.contentBuilder(XContentType.JSON);
+        pathBuilder.startObject().field(name, path).endObject();
+
+        XContentBuilder stringBuilder = XContentFactory.contentBuilder(XContentType.JSON);
+        stringBuilder.startObject().field(name, path.toString()).endObject();
+
+        assertThat(pathBuilder.string(), equalTo(stringBuilder.string()));
+    }
+
+    @Test
+    public void testHandlingOfCollectionOfPaths() throws IOException {
+        Path path = PathUtils.get("path");
+
+        XContentBuilder pathBuilder = XContentFactory.contentBuilder(XContentType.JSON);
+        pathBuilder.startObject().field("file", Arrays.asList(path)).endObject();
+
+        XContentBuilder stringBuilder = XContentFactory.contentBuilder(XContentType.JSON);
+        stringBuilder.startObject().field("file", Arrays.asList(path.toString())).endObject();
+
+        assertThat(pathBuilder.string(), equalTo(stringBuilder.string()));
+    }
+
 }