LPS-179319 springboot known issue, don't use application.properties in modules spring-projects/spring-boot#24688

Author: gamerson

modules/util/client-extension-util-spring-boot/src/main/java/com/liferay/client/extension/util/spring/boot/LiferayOAuth2ClientConfiguration.java

@@ -146,10 +146,7 @@ private ClientRegistration[] _getClientRegistrations() {
 					".oauth2.headless.server.client.secret");
 
 			if (clientSecret == null) {
-				throw new IllegalArgumentException(
-					"Property \"" + externalReferenceCode +
-						".oauth2.headless.server.client.secret\" is not " +
-							"defined");
+				continue;
 			}
 
 			String tokenURI = _environment.getProperty(