diff --git a/pom.xml b/pom.xml
index fb3b5f3..47d244b 100644
--- a/pom.xml
+++ b/pom.xml
@@ -13,7 +13,6 @@
         <java.version>8</java.version>
         <maven.compiler.source>1.8</maven.compiler.source>
         <maven.compiler.target>1.8</maven.compiler.target>
-        <jackson.version>2.13.5</jackson.version>
         <commons-lang3.version>3.13.0</commons-lang3.version>
         <guava.version>32.1.3-jre</guava.version>
         <google-jsr305.version>3.0.2</google-jsr305.version>
@@ -21,12 +20,6 @@
     </properties>
 
     <dependencies>
-        <dependency>
-            <groupId>com.fasterxml.jackson.core</groupId>
-            <artifactId>jackson-annotations</artifactId>
-            <version>${jackson.version}</version>
-        </dependency>
-
         <dependency>
             <groupId>com.google.guava</groupId>
             <artifactId>guava</artifactId>
diff --git a/src/main/java/xyz/zhouxy/plusone/commons/domain/ValidatableStringRecord.java b/src/main/java/xyz/zhouxy/plusone/commons/domain/ValidatableStringRecord.java
index 794861e..8cf859d 100644
--- a/src/main/java/xyz/zhouxy/plusone/commons/domain/ValidatableStringRecord.java
+++ b/src/main/java/xyz/zhouxy/plusone/commons/domain/ValidatableStringRecord.java
@@ -16,11 +16,11 @@
 
 package xyz.zhouxy.plusone.commons.domain;
 
+import java.util.Objects;
 import java.util.regex.Pattern;
 
 import org.apache.commons.lang3.StringUtils;
 
-import com.fasterxml.jackson.annotation.JsonValue;
 import com.google.common.base.Preconditions;
 
 import xyz.zhouxy.plusone.commons.util.RegexTools;
@@ -37,7 +37,7 @@ public abstract class ValidatableStringRecord
 
     protected ValidatableStringRecord(String value, Pattern pattern) {
         Preconditions.checkNotNull(pattern, "The pattern must not be null.");
-        Preconditions.checkArgument(StringUtils.isNotBlank(value), "The value must be has text.");
+        Preconditions.checkNotNull(StringUtils.isNotBlank(value), "The value must not be null.");
         Preconditions.checkArgument(RegexTools.matches(value, pattern));
         this.value = value;
     }
@@ -47,7 +47,6 @@ public abstract class ValidatableStringRecord
      * 
      * @return 字符串（不为空）
      */
-    @JsonValue
     public final String value() {
         return this.value;
     }
@@ -57,6 +56,23 @@ public abstract class ValidatableStringRecord
         return this.value.compareTo(o.value);
     }
 
+    @Override
+    public int hashCode() {
+        return Objects.hash(value);
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (this == obj)
+            return true;
+        if (obj == null)
+            return false;
+        if (getClass() != obj.getClass())
+            return false;
+        ValidatableStringRecord other = (ValidatableStringRecord) obj;
+        return Objects.equals(value, other.value);
+    }
+
     @Override
     public String toString() {
         return this.value();
diff --git a/src/main/java/xyz/zhouxy/plusone/commons/util/RestfulResult.java b/src/main/java/xyz/zhouxy/plusone/commons/util/RestfulResult.java
index 968563c..16a6b49 100644
--- a/src/main/java/xyz/zhouxy/plusone/commons/util/RestfulResult.java
+++ b/src/main/java/xyz/zhouxy/plusone/commons/util/RestfulResult.java
@@ -21,7 +21,6 @@ import java.util.function.Supplier;
 
 import javax.annotation.Nullable;
 
-import com.fasterxml.jackson.annotation.JsonInclude;
 import com.google.common.base.Preconditions;
 
 /**
@@ -31,7 +30,6 @@ import com.google.common.base.Preconditions;
  * @deprecated 已被 {@link UnifiedResponse} 代替。
  */
 @Deprecated
-@JsonInclude(JsonInclude.Include.NON_NULL)
 public class RestfulResult {
 
     public static final int SUCCESS_STATUS = 2000000;