Can excluding transitive dependencies break my code?

I need artifact A. So, I included it in my pom.xml

<dependency>
      <groupId>some.group</groupId>
      <artifactId>some.artifact</artifactId>
      <version>some.version</version>
</dependency

The artifact A uses artifact B which I absolutely don't want to be copied to my classpath. So, I used exclusions for B

<dependency>
     <groupId>some.group</groupId>
     <artifactId>some.artifact</artifactId>
     <version>some.version</version>
      <exclusions>
         <exclusion>
             <groupId>dontwant.group</groupId>
             <artifactId>dontwant.artifact</artifactId>
         </exclusion>
     <exclusions>
</dependency

I don't have a dependency on B. But, I do have dependency on A and A depends on B. B is now not being copied to the classpath. Can this break my code ?

You use dependency A, A uses dependency B, but you excluded B from A. What is going to happen?

• Your compilation may or may not break, depending on how A exactly depends on B. But this is not the real issue
• At runtime, when you use A, and A tries to call B, the code will break. ClassNotFoundException, to be precise. There are cases in which this does not happen, e.g. if A uses B only in some obscure methods and you never call those methods. But, as a rule of thumb, it will probably fail.

So avoid the exclusions, and put B onto the classpath unless you have very good reason not to (and you should add that reason to the question).