add matchIfMissing

spring-boot-starter/starter-security/src/main/java/org/camunda/bpm/spring/boot/starter/security/oauth2/CamundaSpringSecurityOAuth2AutoConfiguration.java

@@ -88,7 +88,7 @@ public FilterRegistrationBean<?> webappAuthenticationFilter() {
   }
 
   @Bean
-  @ConditionalOnProperty(name = "identity-provider.enabled", havingValue = "true", prefix = OAuth2Properties.PREFIX)
+  @ConditionalOnProperty(name = "identity-provider.enabled", havingValue = "true", prefix = OAuth2Properties.PREFIX, matchIfMissing = true)
   public OAuth2IdentityProviderPlugin identityProviderPlugin() {
     logger.debug("Registering OAuth2IdentityProviderPlugin");
     return new OAuth2IdentityProviderPlugin();