public void setPrincipal(EntityIdentifier principal) {
        this.principal = principal;
    }
<p>
The principal specified in the policy's scope. This element isn't included in the response when
<code>Principal</code> isn't present in the policy content.
</p>

@param principal
       The principal specified in the policy's scope. This element isn't included in the response when
       <code>Principal</code> isn't present in the policy content.
aws-java-sdk-verifiedpermissions/src/main/java/com/amazonaws/services/verifiedpermissions/model/UpdatePolicyResult.java