FilesystemMetadataResolver idpMetadataResolver = new  FilesystemMetadataResolver(new File("C:\idp_metadata.xml"));
    idpMetadataResolver.setRequireValidMetadata(true);
    idpMetadataResolver.setParserPool(new BasicParserPool());
    idpMetadataResolver.initialize();

    MetadataCredentialResolver credentialResolver = new MetadataCredentialResolver();

    credentialResolver.setRoleDescriptorResolver(new BasicRoleDescriptorResolver(idpMetadataResolver));

    CriteriaSet criteriaSet = new CriteriaSet();
    criteriaSet.add(new EntityIdCriterion("https://idp.ssocircle.com"));
    criteriaSet.add(new EntityRoleCriterion(IDPSSODescriptor.DEFAULT_ELEMENT_NAME));

    X509Credential credential = (X509Credential)credentialResolver.resolveSingle(criteriaSet);

net.shibboleth.utilities.java.support.component.ComponentInitializationException: Component identifier can not be null
at net.shibboleth.utilities.java.support.component.AbstractIdentifiedInitializableComponent.doInitialize(AbstractIdentifiedInitializableComponent.java:65)
at org.opensaml.saml.metadata.resolver.impl.AbstractMetadataResolver.doInitialize(AbstractMetadataResolver.java:188)
at net.shibboleth.utilities.java.support.component.AbstractInitializableComponent.initialize(AbstractInitializableComponent.java:61)

FilesystemMetadataResolver idpMetadataResolver = new FilesystemMetadataResolver(new File("C:\idp.xml"));
    idpMetadataResolver.setRequireValidMetadata(true);
    idpMetadataResolver.setParserPool(XMLObjectProviderRegistrySupport.getParserPool());
    idpMetadataResolver.setId("someidentifier");
    idpMetadataResolver.initialize();