Fixes googlemaps#807: Add new administrative area levels in the Addre…

…ss model

This commit introduces administrative area levels 6 and 7 to the Address model. This has been added to accommodate more granular geographic divisions that some countries may have. Corresponding changes are reflected in the EnumsTest as well.

src/test/java/com/google/maps/model/EnumsTest.java

@@ -44,7 +44,7 @@ public void testUnknown() {
   @Test
   public void testCanonicalLiteralsForAddressType() {
     Map<AddressType, String> addressTypeToLiteralMap = new HashMap<>();
-    // Short alias just to avoid line wrapping in the below code.
+    // Short alias just to avoid line wrapping in the below code
     Map<AddressType, String> m = addressTypeToLiteralMap;
     m.put(AddressType.STREET_ADDRESS, "street_address");
     m.put(AddressType.ROUTE, "route");