public void setAddPrincipals(java.util.Collection<String> addPrincipals) {
        if (addPrincipals == null) {
            this.addPrincipals = null;
            return;
        }

        this.addPrincipals = new java.util.ArrayList<String>(addPrincipals);
    }
<p>
The principals to add to the cross-account attachment. A principal is an account or the Amazon Resource Name
(ARN) of an accelerator that the attachment gives permission to work with resources from another account. The
resources are also listed in the attachment.
</p>
<p>
To add more than one principal, separate the account numbers or accelerator ARNs, or both, with commas.
</p>

@param addPrincipals
       The principals to add to the cross-account attachment. A principal is an account or the Amazon Resource
       Name (ARN) of an accelerator that the attachment gives permission to work with resources from another
       account. The resources are also listed in the attachment.</p>
       <p>
       To add more than one principal, separate the account numbers or accelerator ARNs, or both, with commas.
aws-java-sdk-globalaccelerator/src/main/java/com/amazonaws/services/globalaccelerator/model/UpdateCrossAccountAttachmentRequest.java