Fix serialization for HitExtractorProcessor

Also get more information when SQL fails in IT.

Original commit: elastic/x-pack-elasticsearch@09f6625274

qa/sql/src/main/java/org/elasticsearch/xpack/sql/RestSqlTestCase.java

@@ -22,7 +22,6 @@ import java.util.HashMap;
 import java.util.Map;
 
 import static java.util.Collections.emptyList;
-import static java.util.Collections.emptyMap;
 import static java.util.Collections.singletonList;
 import static java.util.Collections.singletonMap;
 import static java.util.Collections.unmodifiableMap;
@@ -161,7 +160,7 @@ public abstract class RestSqlTestCase extends ESRestTestCase {
     }
 
     private Map<String, Object> runSql(HttpEntity sql) throws IOException {
-        Response response = client().performRequest("POST", "/_sql", emptyMap(), sql);
+        Response response = client().performRequest("POST", "/_sql", singletonMap("error_trace", "true"), sql);
         try (InputStream content = response.getEntity().getContent()) {
             return XContentHelper.convertToMap(JsonXContent.jsonXContent, content, false);
         }

sql/cli/src/test/java/org/elasticsearch/xpack/sql/cli/ExplainIT.java

@@ -27,14 +27,14 @@ public class ExplainIT extends CliIntegrationTestCase {
         assertThat(in.readLine(), startsWith("----------"));
         assertThat(in.readLine(), startsWith("Project[[test_field{r}#"));
         assertThat(in.readLine(), startsWith("\\_SubQueryAlias[test]"));
-        assertThat(in.readLine(), startsWith("  \\EsRelation[test][test_field{r}#"));
+        assertThat(in.readLine(), startsWith("  \\_EsRelation[test][test_field{r}#"));
         assertEquals("", in.readLine());
 
         command("EXPLAIN (PLAN OPTIMIZED) SELECT * FROM test");
         assertThat(in.readLine(), containsString("plan"));
         assertThat(in.readLine(), startsWith("----------"));
         assertThat(in.readLine(), startsWith("Project[[test_field{r}#"));
-        assertThat(in.readLine(), startsWith("\\EsRelation[test][test_field{r}#"));
+        assertThat(in.readLine(), startsWith("\\_EsRelation[test][test_field{r}#"));
         assertEquals("", in.readLine());
 
         // TODO in this case we should probably remove the source filtering entirely. Right? It costs but we don't need it.
@@ -71,7 +71,7 @@ public class ExplainIT extends CliIntegrationTestCase {
         assertThat(in.readLine(), startsWith("Project[[i{r}#"));
         assertThat(in.readLine(), startsWith("\\_Filter[i{r}#"));
         assertThat(in.readLine(), startsWith("  \\_SubQueryAlias[test]"));
-        assertThat(in.readLine(), startsWith("    \\EsRelation[test][i{r}#"));
+        assertThat(in.readLine(), startsWith("    \\_EsRelation[test][i{r}#"));
         assertEquals("", in.readLine());
 
         command("EXPLAIN (PLAN OPTIMIZED) SELECT * FROM test WHERE i = 2");
@@ -79,7 +79,7 @@ public class ExplainIT extends CliIntegrationTestCase {
         assertThat(in.readLine(), startsWith("----------"));
         assertThat(in.readLine(), startsWith("Project[[i{r}#"));
         assertThat(in.readLine(), startsWith("\\_Filter[i{r}#"));
-        assertThat(in.readLine(), startsWith("  \\EsRelation[test][i{r}#"));
+        assertThat(in.readLine(), startsWith("  \\_EsRelation[test][i{r}#"));
         assertEquals("", in.readLine());
 
         command("EXPLAIN (PLAN EXECUTABLE) SELECT * FROM test WHERE i = 2");
@@ -124,14 +124,14 @@ public class ExplainIT extends CliIntegrationTestCase {
         assertThat(in.readLine(), startsWith("----------"));
         assertThat(in.readLine(), startsWith("Aggregate[[],[COUNT(1)#"));
         assertThat(in.readLine(), startsWith("\\_SubQueryAlias[test]"));
-        assertThat(in.readLine(), startsWith("  \\EsRelation[test][i{r}#"));
+        assertThat(in.readLine(), startsWith("  \\_EsRelation[test][i{r}#"));
         assertEquals("", in.readLine());
 
         command("EXPLAIN (PLAN OPTIMIZED) SELECT COUNT(*) FROM test");
         assertThat(in.readLine(), containsString("plan"));
         assertThat(in.readLine(), startsWith("----------"));
         assertThat(in.readLine(), startsWith("Aggregate[[],[COUNT(1)#"));
-        assertThat(in.readLine(), startsWith("\\EsRelation[test][i{r}#"));
+        assertThat(in.readLine(), startsWith("\\_EsRelation[test][i{r}#"));
         assertEquals("", in.readLine());
 
         command("EXPLAIN (PLAN EXECUTABLE) SELECT COUNT(*) FROM test");

sql/jdbc/src/test/java/org/elasticsearch/xpack/sql/jdbc/DebugSqlSpec.java

@@ -15,7 +15,7 @@ import java.nio.file.Path;
 import java.util.List;
 
 @TestLogging(JdbcTestUtils.SQL_TRACE)
-public class DebugSqlSpec extends SqlSpecIT {
+public abstract class DebugSqlSpec extends SqlSpecIT {
     public static LocalH2 H2 = new LocalH2();
 
     @ParametersFactory(argumentFormatting = PARAM_FORMATTING)

sql/server/src/main/java/org/elasticsearch/xpack/sql/expression/function/scalar/processor/runtime/HitExtractorProcessor.java

@@ -34,7 +34,7 @@ public class HitExtractorProcessor implements Processor {
 
     @Override
     public void writeTo(StreamOutput out) throws IOException {
-        extractor.writeTo(out);
+        out.writeNamedWriteable(extractor);
     }
 
     @Override