test: pin getObject(int, Map) null/empty fast path

Drive-by pin test: StreamingResultSet.getObject(int, Map<String,Class<?>>)
with a null or empty type map should behave like plain getObject(int)
per the JDBC spec. Previously not asserted anywhere.

The companion getObject(Class) fallback test landed earlier on this
branch, bundled into the QueryJDBCAccessor base-class fix commit so
the fix and its end-to-end coverage ship as a single cherry-pickable
unit.

Author: mkaufmann

jdbc-core/src/test/java/com/salesforce/datacloud/jdbc/core/StreamingResultSetMethodTest.java

@@ -202,6 +202,18 @@ void getObjectWithClassUsesAccessorBaseFallback() throws Exception {
         }
     }
 
+    @Test
+    void getObjectWithNullTypeMapBehavesLikeGetObject() throws Exception {
+        // JDBC: getObject(int, Map) with a null/empty type map should behave like getObject(int).
+        try (val rs = createResultSet()) {
+            rs.next();
+            val plain = rs.getObject(1);
+            assertThat(rs.getObject(1, (java.util.Map<String, Class<?>>) null)).isEqualTo(plain);
+            assertThat(rs.getObject(1, java.util.Collections.<String, Class<?>>emptyMap()))
+                    .isEqualTo(plain);
+        }
+    }
+
     @Test
     void queryId() throws Exception {
         try (val rs = createResultSet()) {