[CALCITE-4970] Support type conversion when no conversion necessary

core/src/main/java/org/apache/calcite/avatica/util/AbstractCursor.java

@@ -423,6 +423,10 @@ public Reader getNCharacterStream() throws SQLException {
     }
 
     public <T> T getObject(Class<T> type) throws SQLException {
+      Object val = getObject();
+      if (val == null || type == null || type.isAssignableFrom(val.getClass())) {
+        return (T) val;
+      }
       throw cannotConvert("Object (with type)");
     }
   }

core/src/test/java/org/apache/calcite/avatica/util/NumberAccessorTest.java

@@ -50,6 +50,26 @@ public void testBigDecimalZeroScale() throws SQLException {
     assertEquals(orig, accessor.getBigDecimal(0));
   }
 
+
+  @Test
+  public void testGetLongObjectWithType() throws SQLException {
+    final Long orig = 1337L;
+    NumberAccessor accessor = new AbstractCursor.NumberAccessor(
+        new Getter() {
+          @Override public Object getObject() {
+            return orig;
+          }
+
+          @Override public boolean wasNull() {
+            return false;
+          }
+        },
+        0);
+
+    assertEquals(orig, accessor.getObject(Long.class));
+  }
+
+
 }
 
 // End NumberAccessorTest.java