security/subsystem/src/main/java/org/jboss/as/security/elytron/ElytronIntegrationResourceDefinitions.java
public static ResourceDefinition getElytronKeyStoreResourceDefinition() {
        final AttributeDefinition[] attributes = new AttributeDefinition[] {LEGACY_JSSE_CONFIG};
        final AbstractAddStepHandler addHandler = new BasicAddHandler<KeyStore>(attributes, KEY_STORE_RUNTIME_CAPABILITY) {

            @Override
            protected BasicService.ValueSupplier<KeyStore> getValueSupplier(ServiceBuilder<KeyStore> serviceBuilder, OperationContext context, ModelNode model) throws OperationFailedException {
                final String legacyJSSEConfig = asStringIfDefined(context, LEGACY_JSSE_CONFIG, model);
                final InjectedValue<SecurityDomainContext> securityDomainContextInjector = new InjectedValue<>();
                if (legacyJSSEConfig != null) {
                    serviceBuilder.addDependency(SecurityDomainService.SERVICE_NAME.append(legacyJSSEConfig), SecurityDomainContext.class, securityDomainContextInjector);
                }

                return () -> {
                    final SecurityDomainContext domainContext = securityDomainContextInjector.getValue();
                    final JSSESecurityDomain jsseDomain = domainContext.getJSSE();
                    if (jsseDomain == null) {
                        throw SecurityLogger.ROOT_LOGGER.unableToLocateJSSEConfig(legacyJSSEConfig);
                    }
                    final KeyStore keyStore = jsseDomain.getKeyStore();
                    if (keyStore == null) {
                        throw SecurityLogger.ROOT_LOGGER.unableToLocateComponentInJSSEDomain("KeyStore", legacyJSSEConfig);
                    }
                    return keyStore;
                };
            }
        };

        return new BasicResourceDefinition(Constants.ELYTRON_KEY_STORE, addHandler, attributes, KEY_STORE_RUNTIME_CAPABILITY);
    }
public static ResourceDefinition getElytronKeyStoreResourceDefinition() {
        final AttributeDefinition[] attributes = new AttributeDefinition[] {LEGACY_JSSE_CONFIG};
        final AbstractAddStepHandler addHandler = new BasicAddHandler<KeyStore>(attributes, KEY_STORE_RUNTIME_CAPABILITY) {

            @Override
            protected BasicService.ValueSupplier<KeyStore> getValueSupplier(ServiceBuilder<KeyStore> serviceBuilder, OperationContext context, ModelNode model) throws OperationFailedException {
                final String legacyJSSEConfig = asStringIfDefined(context, LEGACY_JSSE_CONFIG, model);
                final InjectedValue<SecurityDomainContext> securityDomainContextInjector = new InjectedValue<>();
                if (legacyJSSEConfig != null) {
                    serviceBuilder.addDependency(SecurityDomainService.SERVICE_NAME.append(legacyJSSEConfig), SecurityDomainContext.class, securityDomainContextInjector);
                }

                return () -> {
                    final SecurityDomainContext domainContext = securityDomainContextInjector.getValue();
                    final JSSESecurityDomain jsseDomain = domainContext.getJSSE();
                    if (jsseDomain == null) {
                        throw SecurityLogger.ROOT_LOGGER.unableToLocateJSSEConfig(legacyJSSEConfig);
                    }
                    final KeyStore keyStore = jsseDomain.getKeyStore();
                    if (keyStore == null) {
                        throw SecurityLogger.ROOT_LOGGER.unableToLocateComponentInJSSEDomain("KeyStore", legacyJSSEConfig);
                    }
                    return keyStore;
                };
            }
        };

        return new BasicResourceDefinition(Constants.ELYTRON_KEY_STORE, addHandler, attributes, KEY_STORE_RUNTIME_CAPABILITY);
    }
Defines a resource that represents an Elytron-compatible key store that can be exported by a JSSE-enabled domain
in the legacy security subsystem.

To export the key store the resource uses a {@code BasicAddHandler} implementation that registers the elytron key-store
capability and implements a {@code org.jboss.as.security.elytron.BasicService.ValueSupplier} that uses the injected
{@code SecurityDomainContext} to obtain a {@code JSSESecurityDomain}. If such domain is found, its configured key
store is obtained and returned.

The {@code ValueSupplier} implementation throws an exception if the referenced legacy domain is not a JSSE-enabled
domain or if the domain doesn't contain a key store configuration.