diff --git a/build.gradle b/build.gradle
index a95aeae..ca04416 100644
--- a/build.gradle
+++ b/build.gradle
@@ -20,6 +20,9 @@ dependencies {
     // spring
     implementation 'org.springframework.boot:spring-boot-starter'
 
+    // spring validation
+    implementation 'org.springframework.boot:spring-boot-starter-validation'
+
     // web
     implementation 'org.springframework.boot:spring-boot-starter-web'
 
diff --git a/src/main/java/io/wwan13/wintersecurity/config/JwtProviderConfigurer.java b/src/main/java/io/wwan13/wintersecurity/config/JwtProviderConfigurer.java
index bb0d163..5210f10 100644
--- a/src/main/java/io/wwan13/wintersecurity/config/JwtProviderConfigurer.java
+++ b/src/main/java/io/wwan13/wintersecurity/config/JwtProviderConfigurer.java
@@ -18,7 +18,9 @@
 
 import io.wwan13.wintersecurity.jwt.support.JwtPropertiesRegistry;
 
+import javax.validation.constraints.NotNull;
+
 public interface JwtProviderConfigurer extends SecretKeyConfigurer {
 
-    void configureJwt(JwtPropertiesRegistry registry);
+    void configureJwt(@NotNull JwtPropertiesRegistry registry);
 }
diff --git a/src/main/java/io/wwan13/wintersecurity/config/SecretKeyConfigurer.java b/src/main/java/io/wwan13/wintersecurity/config/SecretKeyConfigurer.java
index 39aab43..47a2cd1 100644
--- a/src/main/java/io/wwan13/wintersecurity/config/SecretKeyConfigurer.java
+++ b/src/main/java/io/wwan13/wintersecurity/config/SecretKeyConfigurer.java
@@ -18,7 +18,9 @@
 
 import io.wwan13.wintersecurity.secretkey.support.SecretKeyRegistry;
 
+import javax.validation.constraints.NotNull;
+
 public interface SecretKeyConfigurer {
 
-    void configureSecretKey(SecretKeyRegistry registry);
+    void configureSecretKey(@NotNull SecretKeyRegistry registry);
 }
diff --git a/src/main/java/io/wwan13/wintersecurity/config/SecureRequestConfigurer.java b/src/main/java/io/wwan13/wintersecurity/config/SecureRequestConfigurer.java
index 924b65b..741b747 100644
--- a/src/main/java/io/wwan13/wintersecurity/config/SecureRequestConfigurer.java
+++ b/src/main/java/io/wwan13/wintersecurity/config/SecureRequestConfigurer.java
@@ -19,9 +19,12 @@
 import io.wwan13.wintersecurity.auth.authpattern.support.AuthPatternsRegistry;
 import io.wwan13.wintersecurity.resolve.support.TargetAnnotationsRegistry;
 
+import javax.validation.constraints.NotNull;
+
 public interface SecureRequestConfigurer extends SecretKeyConfigurer {
 
-    void registerAuthPatterns(AuthPatternsRegistry registry);
+    void registerAuthPatterns(@NotNull AuthPatternsRegistry registry);
 
-    void registerTargetAnnotations(TargetAnnotationsRegistry registry);
+    default void registerTargetAnnotations(@NotNull TargetAnnotationsRegistry registry) {
+    }
 }