Fixed AI review comments, minor code-style update in MailtrapClient

Author: vitalii-t

README.md

@@ -143,8 +143,7 @@ Bulk stream example (optional) differs only by setting `.bulk(true)` instead of
 ```java
         final MailtrapConfig config = new MailtrapConfig.Builder()
     .token(TOKEN)
-    .sandbox(true)
-    .inboxId(INBOX_ID)
+    .bulk(true)
     .build();
 ```
 
@@ -184,14 +183,12 @@ public class SwitchSendFromClient {
         // Production send
         client.send(mail);
 
-        client.switchToBulkSendingApi();
-        
         // Bulk send
+        client.switchToBulkSendingApi();
         client.send(mail);
 
-        client.switchToEmailTestingApi(INBOX_ID);
-
         // Sandbox send
+        client.switchToEmailTestingApi(INBOX_ID);
         client.send(mail);
     }
 
@@ -311,7 +308,7 @@ public class FullFeaturedExample {
     }
 
     private static String readAndEncodeAttachment(final String filename) {
-        try (final InputStream inputStream = EverythingExample.class.getClassLoader().getResourceAsStream(filename)) {
+        try (final InputStream inputStream = FullFeaturedExample.class.getClassLoader().getResourceAsStream(filename)) {
             if (inputStream == null) {
                 return "";
             }

src/main/java/io/mailtrap/client/MailtrapClient.java

@@ -108,7 +108,7 @@ public void switchToBulkSendingApi() {
      *
      * @param inboxId the inbox ID to use for testing
      */
-    public void switchToEmailTestingApi(Long inboxId) {
+    public void switchToEmailTestingApi(final Long inboxId) {
         this.sendingContextHolder.setInboxId(inboxId);
         this.sendingContextHolder.setSandbox(true);
         this.sendingContextHolder.setBulk(false);