public String getExternalId() {
        return this.externalId;
    }
<p>
A unique identifier that is used by third parties when assuming roles in
their customers' accounts. For each role that the third party can assume,
they should instruct their customers to ensure the role's trust policy
checks for the external ID that the third party generated. Each time the
third party assumes the role, they should pass the customer's external
ID. The external ID is useful in order to help third parties bind a role
to the customer who created it. For more information about the external
ID, see <a href=
"http://docs.aws.amazon.com/IAM/latest/UserGuide/id_roles_create_for-user_externalid.html"
>How to Use an External ID When Granting Access to Your AWS Resources to
a Third Party</a> in the <i>Using IAM</i>.
</p>

@return A unique identifier that is used by third parties when assuming
        roles in their customers' accounts. For each role that the third
        party can assume, they should instruct their customers to ensure
        the role's trust policy checks for the external ID that the third
        party generated. Each time the third party assumes the role, they
        should pass the customer's external ID. The external ID is useful
        in order to help third parties bind a role to the customer who
        created it. For more information about the external ID, see <a
        href=
        "http://docs.aws.amazon.com/IAM/latest/UserGuide/id_roles_create_for-user_externalid.html"
        >How to Use an External ID When Granting Access to Your AWS
        Resources to a Third Party</a> in the <i>Using IAM</i>.
aws-java-sdk-core/src/main/java/com/amazonaws/auth/profile/internal/securitytoken/RoleInfo.java