test: NbpServiceTest completed?

src/main/java/eu/ztsh/wymiana/config/RestClientConfiguration.java

@@ -0,0 +1,18 @@
+package eu.ztsh.wymiana.config;
+
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.web.client.RestClient;
+
+@Configuration
+public class RestClientConfiguration {
+
+    @Bean
+    public RestClient restClient() {
+        return RestClient.builder()
+            .baseUrl("http://api.nbp.pl")
+            .defaultHeader("Accept", "application/json")
+            .build();
+    }
+
+}