protected MessageHandler buildCheckExpectedIssuer() throws ComponentInitializationException {
        val expectedIssuer = new CheckExpectedIssuer();
        expectedIssuer.setIssuerLookupStrategy(new IssuerFunction());
        expectedIssuer.setExpectedIssuerLookupStrategy(messageContext -> idpMetadataResolver.getEntityId());
        expectedIssuer.initialize();
        return expectedIssuer;
    }
<p>buildCheckExpectedIssuer.</p>

@return a {@link MessageHandler} object
@throws ComponentInitializationException if any.
pac4j-saml/src/main/java/org/pac4j/saml/sso/artifact/DefaultSOAPPipelineFactory.java