Remove redundant superinterface.
diff --git a/src/main/java/org/apache/commons/compress/archivers/zip/X0014_X509Certificates.java b/src/main/java/org/apache/commons/compress/archivers/zip/X0014_X509Certificates.java
index 2a13d88..79c3f18 100644
--- a/src/main/java/org/apache/commons/compress/archivers/zip/X0014_X509Certificates.java
+++ b/src/main/java/org/apache/commons/compress/archivers/zip/X0014_X509Certificates.java
@@ -40,7 +40,7 @@
  * @NotThreadSafe
  * @since 1.11
  */
-public class X0014_X509Certificates extends PKWareExtraHeader implements ZipExtraField {
+public class X0014_X509Certificates extends PKWareExtraHeader {
     private static final long serialVersionUID = 1L;
 
     public X0014_X509Certificates() {
diff --git a/src/main/java/org/apache/commons/compress/archivers/zip/X0015_CertificateIdForFile.java b/src/main/java/org/apache/commons/compress/archivers/zip/X0015_CertificateIdForFile.java
index 3253482..0342dc3 100644
--- a/src/main/java/org/apache/commons/compress/archivers/zip/X0015_CertificateIdForFile.java
+++ b/src/main/java/org/apache/commons/compress/archivers/zip/X0015_CertificateIdForFile.java
@@ -41,7 +41,7 @@
  * @NotThreadSafe
  * @since 1.11
  */
-public class X0015_CertificateIdForFile extends PKWareExtraHeader implements ZipExtraField {
+public class X0015_CertificateIdForFile extends PKWareExtraHeader {
     private static final long serialVersionUID = 1L;
 
     public X0015_CertificateIdForFile() {
diff --git a/src/main/java/org/apache/commons/compress/archivers/zip/X0016_CertificateIdForCentralDirectory.java b/src/main/java/org/apache/commons/compress/archivers/zip/X0016_CertificateIdForCentralDirectory.java
index ae79b07..35fe25f8 100644
--- a/src/main/java/org/apache/commons/compress/archivers/zip/X0016_CertificateIdForCentralDirectory.java
+++ b/src/main/java/org/apache/commons/compress/archivers/zip/X0016_CertificateIdForCentralDirectory.java
@@ -42,7 +42,7 @@
  * @NotThreadSafe
  * @since 1.11
  */
-public class X0016_CertificateIdForCentralDirectory extends PKWareExtraHeader implements ZipExtraField {
+public class X0016_CertificateIdForCentralDirectory extends PKWareExtraHeader {
     private static final long serialVersionUID = 1L;
 
     public X0016_CertificateIdForCentralDirectory() {
diff --git a/src/main/java/org/apache/commons/compress/archivers/zip/X0017_StrongEncryptionHeader.java b/src/main/java/org/apache/commons/compress/archivers/zip/X0017_StrongEncryptionHeader.java
index 790731c..1d49d50 100644
--- a/src/main/java/org/apache/commons/compress/archivers/zip/X0017_StrongEncryptionHeader.java
+++ b/src/main/java/org/apache/commons/compress/archivers/zip/X0017_StrongEncryptionHeader.java
@@ -242,7 +242,7 @@
  * @NotThreadSafe
  * @since 1.11
  */
-public class X0017_StrongEncryptionHeader extends PKWareExtraHeader implements ZipExtraField {
+public class X0017_StrongEncryptionHeader extends PKWareExtraHeader {
     private static final long serialVersionUID = 1L;
 
     public X0017_StrongEncryptionHeader() {
diff --git a/src/main/java/org/apache/commons/compress/archivers/zip/X0019_EncryptionRecipientCertificateList.java b/src/main/java/org/apache/commons/compress/archivers/zip/X0019_EncryptionRecipientCertificateList.java
index 935933a..2218f45 100644
--- a/src/main/java/org/apache/commons/compress/archivers/zip/X0019_EncryptionRecipientCertificateList.java
+++ b/src/main/java/org/apache/commons/compress/archivers/zip/X0019_EncryptionRecipientCertificateList.java
@@ -48,7 +48,7 @@
  * @NotThreadSafe
  * @since 1.11
  */
-public class X0019_EncryptionRecipientCertificateList extends PKWareExtraHeader implements ZipExtraField {
+public class X0019_EncryptionRecipientCertificateList extends PKWareExtraHeader {
     private static final long serialVersionUID = 1L;
 
     public X0019_EncryptionRecipientCertificateList() {