Fix resolving url. Add tests. Add docs.

docs/src/main/asciidoc/spring-cloud-openfeign.adoc

@@ -925,6 +925,7 @@ TIP: If you want to run Spring Cloud OpenFeign clients in AOT or native image mo
 
 TIP: If you want to run Spring Cloud OpenFeign clients in AOT or native image modes, ensure `spring.cloud.openfeign.lazy-attributes-resolution` has not been set to `true`.
 
+TIP:  However, if you set the `url` value via properties, it is possible to override the `@FeignClient` `url` value by running the image with `-Dspring.cloud.openfeign.client.config.[clientId].url=[url]` flag. In order to enable overriding, a `url` value also has to be set via properties and not `@FeignClient` attribute during buildtime.
 
 == Configuration properties
 

spring-cloud-openfeign-core/src/main/java/org/springframework/cloud/openfeign/FeignClientFactoryBean.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2013-2022 the original author or authors.
+ * Copyright 2013-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -505,10 +505,7 @@ public class FeignClientFactoryBean
 					"Provide Feign client URL either in @FeignClient() or in config properties.");
 		}
 
-		// TODO: create the appropriate target
 		return new PropertyBasedTarget(type, name, config);
-		// return new HardCodedTarget(type, name,
-		// FeignClientsRegistrar.getUrl(config.getUrl()));
 	}
 
 	private boolean isUrlAvailableInConfig(String contextId) {

spring-cloud-openfeign-core/src/main/java/org/springframework/cloud/openfeign/PropertyBasedTarget.java

@@ -19,10 +19,18 @@ package org.springframework.cloud.openfeign;
 import feign.Target;
 
 /**
+ * A {@link HardCodedTarget} implementation that resolves url from properties when the
+ * initial call is made. Using it allows specifying the url at runtime in an AOT-packaged
+ * application or a native image by setting the value of the
+ * `spring.cloud.openfeign.client.config.[clientId].url`.
+ *
  * @author Olga Maciaszek-Sharma
+ * @see FeignClientProperties.FeignClientConfiguration#getUrl()
  */
 public class PropertyBasedTarget<T> extends Target.HardCodedTarget<T> {
 
+	private String url;
+
 	private final FeignClientProperties.FeignClientConfiguration config;
 
 	public PropertyBasedTarget(Class<T> type, String name, FeignClientProperties.FeignClientConfiguration config) {
@@ -32,7 +40,10 @@ public class PropertyBasedTarget<T> extends Target.HardCodedTarget<T> {
 
 	@Override
 	public String url() {
-		return config.getUrl();
+		if (url == null) {
+			url = config.getUrl();
+		}
+		return url;
 	}
 
 }

spring-cloud-openfeign-core/src/test/java/org/springframework/cloud/openfeign/NonRefreshableFeignClientUrlTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2013-2022 the original author or authors.
+ * Copyright 2013-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -33,6 +33,7 @@ import static org.assertj.core.api.Assertions.assertThat;
 
 /**
  * @author Jasbir Singh
+ * @author Olga Maciaszek-Sharma
  */
 @SpringBootTest
 @TestPropertySource("classpath:feign-properties.properties")
@@ -65,7 +66,7 @@ class NonRefreshableFeignClientUrlTests {
 	public void shouldInstantiateFeignClientWhenUrlFromProperties() {
 		UrlTestClient.UrlResponseForTests response = configBasedClient.test();
 		assertThat(response.getUrl()).isEqualTo("http://localhost:9999/test");
-		assertThat(response.getTargetType()).isEqualTo(Target.HardCodedTarget.class);
+		assertThat(response.getTargetType()).isEqualTo(PropertyBasedTarget.class);
 	}
 
 	@Test