Normalize trailing slash in store URLs

src/main/java/com/icoderman/woocommerce/oauth/OAuthConfig.java

@@ -12,7 +12,7 @@ public OAuthConfig(String url, String consumerKey, String consumerSecret) {
                 consumerSecret == null || consumerSecret.isEmpty()) {
             throw new IllegalArgumentException("All arguments are required");
         }
-        this.url = url;
+        this.url = url.endsWith("/") ? url.substring(0, url.lastIndexOf("/")) : url;
         this.consumerKey = consumerKey;
         this.consumerSecret = consumerSecret;
     }

src/test/java/com/icoderman/woocommerce/oauth/OAuthConfigTest.java

@@ -0,0 +1,30 @@
+package com.icoderman.woocommerce.oauth;
+
+import org.junit.Test;
+
+import static org.junit.Assert.assertEquals;
+
+public class OAuthConfigTest {
+
+    @Test
+    public void removesOneTrailingSlashFromStoreUrl() {
+        OAuthConfig config = new OAuthConfig(
+                "https://store.example.com/",
+                "consumer-key",
+                "consumer-secret"
+        );
+
+        assertEquals("https://store.example.com", config.getUrl());
+    }
+
+    @Test
+    public void preservesStoreUrlWithoutTrailingSlash() {
+        OAuthConfig config = new OAuthConfig(
+                "https://store.example.com",
+                "consumer-key",
+                "consumer-secret"
+        );
+
+        assertEquals("https://store.example.com", config.getUrl());
+    }
+}