Fix binary docvalue_fields with padding

Previously docvalue_fields for binary values with paddings did not
output padding. We consider it to be a bug because: 1) es would
not be able parse these values 2) output from source filtering
and fields API is different and does output padding.

This patches fixes this by outputing padding for binary
docvalue_fields where it is present.

Closes #70244

Author: mayya-sharipova

modules/lang-painless/src/yamlRestTest/resources/rest-api-spec/test/painless/60_script_doc_values_binary.yml

@@ -27,20 +27,13 @@
 
     - do:
         search:
-            rest_total_hits_as_int: true
             body:
                 script_fields:
-                    field:
+                    field1:
                         script:
                             source: "doc['binary'].get(0).utf8ToString()"
-    - match: { hits.hits.0.fields.field.0: "Some binary blob" }
-
-    - do:
-        search:
-            rest_total_hits_as_int: true
-            body:
-                script_fields:
-                    field:
+                    field2:
                         script:
                             source: "doc['binary'].value.utf8ToString()"
-    - match: { hits.hits.0.fields.field.0: "Some binary blob" }
+    - match: { hits.hits.0.fields.field1.0: "Some binary blob" }
+    - match: { hits.hits.0.fields.field2.0: "Some binary blob" }

rest-api-spec/src/main/resources/rest-api-spec/test/search/350_binary_field.yml

@@ -0,0 +1,49 @@
+---
+"binary":
+    - skip:
+        features: ["headers"]
+        version: " - 7.99.99"
+        reason: "docvalues_fields on binary field were corrected in 8.0"
+    - do:
+        indices.create:
+            index: test
+            body:
+                mappings:
+                    properties:
+                        binary:
+                            type: binary
+                            doc_values: true
+
+    - do:
+        #other formats (e.g. cbor) may not support parsing of binary
+        headers:
+            Content-Type: application/json
+        index:
+            index: test
+            id: 1
+            body:
+                binary: U29tZSBiaW5hcnkgYmxvYg==
+
+    - do:
+        indices.refresh: {}
+
+    - do:
+        search:
+            index: test
+            body:
+                docvalue_fields: [ "binary" ]
+    - match: { hits.hits.0.fields.binary.0: "U29tZSBiaW5hcnkgYmxvYg==" }
+
+    - do:
+        search:
+            index: test
+            body:
+                fields: [ "binary" ]
+    - match: { hits.hits.0.fields.binary.0: "U29tZSBiaW5hcnkgYmxvYg==" }
+
+    - do:
+        search:
+            index: test
+            body:
+                _source: ["binary"]
+    - match: { hits.hits.0._source.binary: "U29tZSBiaW5hcnkgYmxvYg==" }

server/src/internalClusterTest/java/org/elasticsearch/search/fields/SearchFieldsIT.java

@@ -810,7 +810,7 @@ public void testDocValueFields() throws Exception {
         assertThat(searchResponse.getHits().getAt(0).getFields().get("boolean_field").getValue(), equalTo((Object) true));
         assertThat(searchResponse.getHits().getAt(0).getFields().get("text_field").getValue(), equalTo("foo"));
         assertThat(searchResponse.getHits().getAt(0).getFields().get("keyword_field").getValue(), equalTo("foo"));
-        assertThat(searchResponse.getHits().getAt(0).getFields().get("binary_field").getValue(), equalTo("KmQ"));
+        assertThat(searchResponse.getHits().getAt(0).getFields().get("binary_field").getValue(), equalTo("KmQ="));
         assertThat(searchResponse.getHits().getAt(0).getFields().get("ip_field").getValue(), equalTo("::1"));
 
         builder = client().prepareSearch().setQuery(matchAllQuery())
@@ -835,7 +835,7 @@ public void testDocValueFields() throws Exception {
         assertThat(searchResponse.getHits().getAt(0).getFields().get("boolean_field").getValue(), equalTo((Object) true));
         assertThat(searchResponse.getHits().getAt(0).getFields().get("text_field").getValue(), equalTo("foo"));
         assertThat(searchResponse.getHits().getAt(0).getFields().get("keyword_field").getValue(), equalTo("foo"));
-        assertThat(searchResponse.getHits().getAt(0).getFields().get("binary_field").getValue(), equalTo("KmQ"));
+        assertThat(searchResponse.getHits().getAt(0).getFields().get("binary_field").getValue(), equalTo("KmQ="));
         assertThat(searchResponse.getHits().getAt(0).getFields().get("ip_field").getValue(), equalTo("::1"));
 
         builder = client().prepareSearch().setQuery(matchAllQuery())

server/src/main/java/org/elasticsearch/search/DocValueFormat.java

@@ -165,7 +165,6 @@ public void writeTo(StreamOutput out) {
         @Override
         public String format(BytesRef value) {
             return Base64.getEncoder()
-                    .withoutPadding()
                     .encodeToString(Arrays.copyOfRange(value.bytes, value.offset, value.offset + value.length));
         }
 

server/src/test/java/org/elasticsearch/search/DocValueFormatTests.java

@@ -126,10 +126,10 @@ public void testRawFormat() {
 
     public void testBinaryFormat() {
         assertEquals("", DocValueFormat.BINARY.format(new BytesRef()));
-        assertEquals("KmQ", DocValueFormat.BINARY.format(new BytesRef(new byte[] {42, 100})));
+        assertEquals("KmQ=", DocValueFormat.BINARY.format(new BytesRef(new byte[] {42, 100})));
 
         assertEquals(new BytesRef(), DocValueFormat.BINARY.parseBytesRef(""));
-        assertEquals(new BytesRef(new byte[] {42, 100}), DocValueFormat.BINARY.parseBytesRef("KmQ"));
+        assertEquals(new BytesRef(new byte[] {42, 100}), DocValueFormat.BINARY.parseBytesRef("KmQ="));
     }
 
     public void testBooleanFormat() {