nominatim: add postalcode request parameter

Author: karussell

README.md

@@ -77,6 +77,7 @@ The geocoding converter supports the following additional Nominatim parameters,
 - `viewbox`
 - `viewboxlbrt`
 - `bounded` 
+- `postalcode`
 
 **Response**
 

src/main/java/com/graphhopper/converter/resources/ConverterResourceNominatim.java

@@ -39,6 +39,7 @@ public Response handle(@QueryParam("q") @DefaultValue("") String query,
                            @QueryParam("locale") @DefaultValue("") String locale,
                            @QueryParam("viewbox") @DefaultValue("") String viewbox,
                            @QueryParam("bounded") @DefaultValue("") String bounded,
+                           @QueryParam("postalcode") @DefaultValue("") String postalcode,
                            @QueryParam("reverse") @DefaultValue("false") boolean reverse,
                            @QueryParam("point") @DefaultValue("") String point
     ) {
@@ -58,6 +59,9 @@ public Response handle(@QueryParam("q") @DefaultValue("") String query,
                 queryParam("email", nominatimEmail).
                 queryParam("addressdetails", "1");
 
+        if (!postalcode.isEmpty()) {
+            target.queryParam("postalcode", postalcode);
+        }
         if (!locale.isEmpty()) {
             locale = getLocaleFromParameter(locale);
             target = target.queryParam("accept-language", locale);