Apply suggestions from code review

Co-authored-by: Lars Vierbergen <lars.vierbergen@xenit.eu>

thunx-autoconfigure/src/main/java/com/contentgrid/thunx/gateway/autoconfigure/GatewayAutoConfiguration.java

@@ -55,7 +55,7 @@ public OpaInputProvider<Authentication, ServerWebExchange> defaultOpaInputProvid
 
     @Bean
     @ConditionalOnMissingBean
-    @ConditionalOnBean({OpaClient.class})
+    @ConditionalOnBean(OpaClient.class)
     public PolicyDecisionPointClient<Authentication, ServerWebExchange> pdpClient(OpaClient opaClient, OpaQueryProvider<ServerWebExchange> queryProvider, OpaInputProvider<Authentication, ServerWebExchange> inputProvider) {
         return new OpenPolicyAgentPDPClient<>(opaClient, queryProvider, inputProvider);
     }