fix: throw error if route segment is empty or null

Author: StephaneRob

src/main/java/com/meilisearch/sdk/http/URLBuilder.java

@@ -21,6 +21,9 @@ public URLBuilder(String rootRoute) {
     }
 
     public URLBuilder addSubroute(String route) {
+        if (route == null || route.isEmpty()) {
+            throw new IllegalArgumentException("route segment must not be null or empty");
+        }
         routes.append("/");
         routes.append(route);
         return this;

src/test/java/com/meilisearch/sdk/http/URLBuilderTest.java

@@ -5,6 +5,7 @@
 import static org.hamcrest.Matchers.is;
 import static org.junit.jupiter.api.Assertions.assertDoesNotThrow;
 import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;
 
 import java.text.SimpleDateFormat;
 import java.util.Date;
@@ -32,6 +33,14 @@ void addSubrouteWithMultipleRoutes() {
         assertThat(classToTest.getRoutes().toString(), is(equalTo("/route1/route2/route3/route4")));
     }
 
+    @Test
+    void addSubrouteWithNullOrEmptyRoute() {
+        assertThat(
+                assertThrows(IllegalArgumentException.class, () -> classToTest.addSubroute(""))
+                        .getMessage(),
+                is(equalTo("route segment must not be null or empty")));
+    }
+
     @Test
     void addParameterStringInt() {
         classToTest.addParameter("parameter1", 1);