fix: Fix compare message webhook message signature

Author: congminh1254

src/main/java/com/box/sdk/BoxWebHookSignatureVerifier.java

@@ -4,7 +4,6 @@
 import java.nio.charset.Charset;
 import java.security.InvalidKeyException;
 import java.security.MessageDigest;
-import java.util.Arrays;
 import java.util.Collections;
 import java.util.EnumSet;
 import java.util.Map;