Fixed OauthAuthorizationUri not being correctly created

src/main/java/com/bunq/sdk/model/core/OauthAuthorizationUri.java

@@ -42,31 +42,31 @@ public class OauthAuthorizationUri extends BunqModel {
     /**
      * Private variables.
      */
-    private String authorizationUri;
+    private final String authorizationUri;
 
     /**
+     *
      */
-    protected OauthAuthorizationUri(String authorizationUri)
-    {
+    protected OauthAuthorizationUri(String authorizationUri) {
         this.authorizationUri = authorizationUri;
     }
 
     /**
+     *
      */
-    public String getAuthorizationUri()
-    {
+    public String getAuthorizationUri() {
         return this.authorizationUri;
     }
 
     /**
+     *
      */
     public static OauthAuthorizationUri create(
             final OauthResponseType responseType,
             final String redirectUri,
             final OauthClient client
     ) {
-        Map<String, String> allRequestParameter = new HashMap<String, String>()
-        {
+        Map<String, String> allRequestParameter = new HashMap<String, String>() {
             {
                 put(FIELD_REDIRECT_URI, redirectUri);
                 put(FIELD_RESPONSE_TYPE, responseType.toString());
@@ -75,11 +75,12 @@ public static OauthAuthorizationUri create(
         };
 
         return new OauthAuthorizationUri(
-            String.format(determineAuthUriFormat(), HttpUtil.createQueryString(allRequestParameter))
+                String.format(determineAuthUriFormat(), HttpUtil.createQueryString(allRequestParameter))
         );
     }
 
     /**
+     *
      */
     public static OauthAuthorizationUri create(
             OauthResponseType responseType,
@@ -89,31 +90,26 @@ public static OauthAuthorizationUri create(
     ) {
         OauthAuthorizationUri baseUri = create(responseType, redirectUri, client);
 
-        Map<String, String> allAdditionalParameter = new HashMap<String, String>()
-        {
+        Map<String, String> allAdditionalParameter = new HashMap<String, String>() {
             {
                 put(FIELD_STATE, state);
             }
         };
 
         return new OauthAuthorizationUri(
-            baseUri.authorizationUri + HttpUtil.createQueryString(allAdditionalParameter)
+                baseUri.authorizationUri + HttpUtil.getQueryDelimiter() + HttpUtil.createQueryString(allAdditionalParameter)
         );
     }
 
     @Override
     public boolean isAllFieldNull() {
-        if (authorizationUri != null) {
-            return false;
-        }
-
-        return true;
+        return authorizationUri == null;
     }
 
     /**
+     *
      */
-    private static String determineAuthUriFormat()
-    {
+    private static String determineAuthUriFormat() {
         ApiEnvironmentType environmentType = BunqContext.getApiContext().getEnvironmentType();
 
         if (AUTH_URI_ENVIRONMENT_MAP.containsKey(environmentType)) {

src/main/java/com/bunq/sdk/util/HttpUtil.java

@@ -12,6 +12,7 @@ public class HttpUtil {
     protected static final String QUERY_DELIMITER = "&";
 
     /**
+     *
      */
     public static String createQueryString(Map<String, String> allParameter) {
         List<String> encodedParameters = new ArrayList<>();
@@ -22,4 +23,11 @@ public static String createQueryString(Map<String, String> allParameter) {
 
         return String.join(QUERY_DELIMITER, encodedParameters);
     }
+
+    /**
+     * @return String
+     */
+    public static String getQueryDelimiter() {
+        return QUERY_DELIMITER;
+    }
 }

src/test/java/com/bunq/sdk/model/core/OauthAuthorizationUriTest.java

@@ -0,0 +1,25 @@
+package com.bunq.sdk.model.core;
+
+import com.bunq.sdk.BunqSdkTestBase;
+import com.bunq.sdk.model.generated.endpoint.OauthClient;
+import org.junit.Assert;
+import org.junit.Test;
+
+public class OauthAuthorizationUriTest extends BunqSdkTestBase {
+    /**
+     * Test constants.
+     */
+    private static final String TEST_EXPECT_URI = "https://oauth.sandbox.bunq.com/auth?response_type=code&redirect_uri=redirecturi&client_id=null&state=state";
+    private static final String TEST_REDIRECT_URI = "redirecturi";
+    private static final String TEST_STATUS = "status";
+    private static final String TEST_STATE = "state";
+
+    @Test
+    public void testOauthAuthorizationUriCreate() {
+        final String uri = OauthAuthorizationUri.create(
+                OauthResponseType.CODE, TEST_REDIRECT_URI, new OauthClient(TEST_STATUS), TEST_STATE
+        ).getAuthorizationUri();
+
+        Assert.assertEquals(TEST_EXPECT_URI, uri);
+    }
+}