Name expected in an import annotation in Kotlin - spring-boot

Question

I have an Spring Boot App (2.1.6) implemented with Kotlin. Is a Rest api that wants to have oAuth 2 with Keycloak.
I have this code in Java that compiles ok:
package com.talleres.paco.mako.config.security;
import com.fasterxml.jackson.databind.ObjectMapper;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;
import org.springframework.boot.autoconfigure.security.oauth2.resource.ResourceServerProperties;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Import;
import org.springframework.security.config.annotation.method.configuration.EnableGlobalMethodSecurity;
import org.springframework.security.config.annotation.web.builders.HttpSecurity;
import org.springframework.security.config.annotation.web.configuration.EnableWebSecurity;
import org.springframework.security.oauth2.client.OAuth2RestTemplate;
import org.springframework.security.oauth2.client.resource.OAuth2ProtectedResourceDetails;
import org.springframework.security.oauth2.config.annotation.web.configuration.EnableResourceServer;
import org.springframework.security.oauth2.config.annotation.web.configuration.ResourceServerConfigurerAdapter;
import org.springframework.security.oauth2.config.annotation.web.configurers.ResourceServerSecurityConfigurer;
import org.springframework.web.cors.CorsConfigurationSource;
import org.springframework.web.cors.UrlBasedCorsConfigurationSource;
#Configuration
#EnableWebSecurity
#EnableResourceServer
#EnableGlobalMethodSecurity(prePostEnabled = true)
#ConditionalOnProperty(prefix = "rest.security", value = "enabled", havingValue = "true")
#Import({SecurityProperties.class})
public class SecurityConfigurer extends ResourceServerConfigurerAdapter {
#Autowired
private ResourceServerProperties resourceServerProperties;
#Autowired
private SecurityProperties securityProperties;
#Override
public void configure(ResourceServerSecurityConfigurer resources) throws Exception {
resources.resourceId(resourceServerProperties.getResourceId());
}
#Override
public void configure(final HttpSecurity http) throws Exception {
http.cors()
.configurationSource(corsConfigurationSource())
.and()
.headers()
.frameOptions()
.disable()
.and()
.csrf()
.disable()
.authorizeRequests()
.antMatchers(securityProperties.getApiMatcher())
.authenticated();
}
#Bean
public CorsConfigurationSource corsConfigurationSource() {
UrlBasedCorsConfigurationSource source = new UrlBasedCorsConfigurationSource();
if (null != securityProperties.getCorsConfiguration()) {
source.registerCorsConfiguration("/**", securityProperties.getCorsConfiguration());
}
return source;
}
#Bean
public JwtAccessTokenCustomizer jwtAccessTokenCustomizer(ObjectMapper mapper) {
return new JwtAccessTokenCustomizer(mapper);
}
#Bean
public OAuth2RestTemplate oauth2RestTemplate(OAuth2ProtectedResourceDetails details) {
OAuth2RestTemplate oAuth2RestTemplate = new OAuth2RestTemplate(details);
//Prepare by getting access token once
oAuth2RestTemplate.getAccessToken();
return oAuth2RestTemplate;
}
}
When i convert to Kotlin i obtain a syntax error:
package com.talleres.paco.mako.config.security
import com.fasterxml.jackson.databind.ObjectMapper
import org.springframework.beans.factory.annotation.Autowired
import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty
import org.springframework.boot.autoconfigure.security.oauth2.resource.ResourceServerProperties
import org.springframework.context.annotation.Bean
import org.springframework.context.annotation.Configuration
import org.springframework.context.annotation.Import
import org.springframework.security.config.annotation.method.configuration.EnableGlobalMethodSecurity
import org.springframework.security.config.annotation.web.builders.HttpSecurity
import org.springframework.security.config.annotation.web.configuration.EnableWebSecurity
import org.springframework.security.oauth2.client.OAuth2RestTemplate
import org.springframework.security.oauth2.client.resource.OAuth2ProtectedResourceDetails
import org.springframework.security.oauth2.config.annotation.web.configuration.EnableResourceServer
import org.springframework.security.oauth2.config.annotation.web.configuration.ResourceServerConfigurerAdapter
import org.springframework.security.oauth2.config.annotation.web.configurers.ResourceServerSecurityConfigurer
import org.springframework.web.cors.CorsConfigurationSource
import org.springframework.web.cors.UrlBasedCorsConfigurationSource
#Configuration
#EnableWebSecurity
#EnableResourceServer
#EnableGlobalMethodSecurity(prePostEnabled = true)
#ConditionalOnProperty(prefix = "rest.security", value = ["enabled"], havingValue = "true")
#Import({SecurityProperties.class})
class SecurityConfigurer : ResourceServerConfigurerAdapter() {
#Autowired
private val resourceServerProperties: ResourceServerProperties? = null
#Autowired
private val securityProperties: SecurityProperties? = null
#Throws(Exception::class)
override fun configure(resources: ResourceServerSecurityConfigurer) {
resources.resourceId(resourceServerProperties!!.resourceId)
}
#Throws(Exception::class)
override fun configure(http: HttpSecurity) {
http.cors()
.configurationSource(corsConfigurationSource())
.and()
.headers()
.frameOptions()
.disable()
.and()
.csrf()
.disable()
.authorizeRequests()
.antMatchers(securityProperties!!.apiMatcher)
.authenticated()
}
#Bean
fun corsConfigurationSource(): CorsConfigurationSource {
val source = UrlBasedCorsConfigurationSource()
if (securityProperties?.corsConfiguration != null) {
source.registerCorsConfiguration("/**", securityProperties.corsConfiguration);
}
return source
}
#Bean
fun jwtAccessTokenCustomizer(mapper: ObjectMapper): JwtAccessTokenCustomizer {
return JwtAccessTokenCustomizer(mapper)
}
#Bean
fun oauth2RestTemplate(details: OAuth2ProtectedResourceDetails): OAuth2RestTemplate {
val oAuth2RestTemplate = OAuth2RestTemplate(details)
oAuth2RestTemplate.accessToken
return oAuth2RestTemplate
}
}
The error is in the line with the annotation import:
#Import({SecurityProperties.class})
I convert the code from Java to Kotlin with IntelliJ CE. The message is:
> Task :compileKotlin
e: D:\Workspaces\CleanArchitecture\mako\src\main\customized\kotlin\com\talleres\paco\mako\config\security\SecurityConfigurer.kt: (26, 34): Name expected
Thanks in advance.

Answer 1

I guess the tool that converts Java code to Kotlin is not always working. In this case #Import is defined in Java and it expects an array of classes, and you can use it in Kotlin by passing a vararg KClass (actually that works only for annotation's value field, otherwise you need to pass a proper array. More info here).
In other words, you need to change your code to: #Import(SecurityProperties::class).
EDIT: it seems like this issue was reported and fixed years ago: KT-10545. I also tried converting your Java code to Kotlin on my machine (using Kotlin 1.3.41) and the #Import statement was correctly generated.
Something funny, though, happened. The #ConditionalOnProperty line was converted to this:
#ConditionalOnProperty(prefix = "rest.security", value = "enabled", havingValue = "true")
which doesn't compile as "Assigning single elements to varargs in named form is forbidden". I'd be curious to see if it's a regression, as it looks correct in your snippet.