SQL: close ResultSet after asserting (elastic/x-pack-elasticsearch#3601)

The on-closing Connection is closed so there's no leak however closing
the ResultSet is good practice and tests another piece of code as well

Original commit: elastic/x-pack-elasticsearch@3a9cee70a3

qa/sql/src/main/java/org/elasticsearch/xpack/qa/sql/jdbc/JdbcAssert.java

@@ -32,14 +32,13 @@ public class JdbcAssert {
     }
 
     public static void assertResultSets(ResultSet expected, ResultSet actual, Logger logger) throws SQLException {
-        assertResultSetMetadata(expected, actual, logger);
-        assertResultSetData(expected, actual, logger);
-    }
-
-    public static void assertResultSetMetadata(ResultSet expected, ResultSet actual) throws SQLException {
-        assertResultSetMetadata(expected, actual, null);
+        try (ResultSet ex = expected; ResultSet ac = actual) {
+            assertResultSetMetadata(ex, ac, logger);
+            assertResultSetData(ex, ac, logger);
+        }
     }
 
+    // metadata doesn't consume a ResultSet thus it shouldn't close it
     public static void assertResultSetMetadata(ResultSet expected, ResultSet actual, Logger logger) throws SQLException {
         ResultSetMetaData expectedMeta = expected.getMetaData();
         ResultSetMetaData actualMeta = actual.getMetaData();
@@ -98,7 +97,14 @@ public class JdbcAssert {
         }
     }
 
+    // The ResultSet is consumed and thus it should be closed
     public static void assertResultSetData(ResultSet expected, ResultSet actual, Logger logger) throws SQLException {
+        try (ResultSet ex = expected; ResultSet ac = actual) {
+            doAssertResultSetData(ex, ac, logger);
+        }
+    }
+    
+    private static void doAssertResultSetData(ResultSet expected, ResultSet actual, Logger logger) throws SQLException {
         ResultSetMetaData metaData = expected.getMetaData();
         int columns = metaData.getColumnCount();
 
@@ -158,4 +164,4 @@ public class JdbcAssert {
     private static Object getTime(ResultSet rs, int column) throws SQLException {
         return rs.getTime(column, UTC_CALENDAR).getTime();
     }
-}
+}