code: public void setTokens(java.util.Collection<String> tokens) {
          if (tokens == null) {
              this.tokens = null;
              return;
          }
  
          this.tokens = new java.util.ArrayList<String>(tokens);
      }
docs: <p>
  A set of unique strings that you use to create a set of CNAME records that you add to the DNS configuration for
  your domain. When Amazon Pinpoint detects these records in the DNS configuration for your domain, the DKIM
  authentication process is complete. Amazon Pinpoint usually detects these records within about 72 hours of adding
  them to the DNS configuration for your domain.
  </p>
  
  @param tokens
  A set of unique strings that you use to create a set of CNAME records that you add to the DNS
  configuration for your domain. When Amazon Pinpoint detects these records in the DNS configuration for
  your domain, the DKIM authentication process is complete. Amazon Pinpoint usually detects these records
  within about 72 hours of adding them to the DNS configuration for your domain.