remove deprecated methods (#769)

* remove deprecated methods
* ignore differences

Author: elharo

clirr-ignored-differences.xml

@@ -1,7 +1,16 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <!-- see http://www.mojohaus.org/clirr-maven-plugin/examples/ignored-differences.html -->
-
 <differences>
+  <difference>
+    <differenceType>7002</differenceType>
+    <className>com/google/api/client/json/webtoken/*</className>
+    <method>java.lang.String getX509Certificate()</method>
+  </difference>
+  <difference>
+    <differenceType>7002</differenceType>
+    <className>com/google/api/client/json/webtoken/*</className>
+    <method>com.google.api.client.json.webtoken.JsonWebSignature$Header setX509Certificate(java.lang.String)</method>
+  </difference>
    <difference>
      <differenceType>7002</differenceType>
      <className>com/google/api/client/testing/http/MockHttpTransport</className>

google-http-client/src/main/java/com/google/api/client/json/webtoken/JsonWebSignature.java

@@ -277,21 +277,6 @@ public Header setX509Thumbprint(String x509Thumbprint) {
       return this;
     }
 
-    /**
-     * Returns the X.509 certificate chain header parameter contains the X.509 public key
-     * certificate or corresponding to the key used to digitally sign the JWS or {@code null} for
-     * none.
-     *
-     * <p>@deprecated Since release 1.19.1, replaced by {@link #getX509Certificates()}.
-     */
-    @Deprecated
-    public final String getX509Certificate() {
-      if (x509Certificates == null || x509Certificates.isEmpty()) {
-        return null;
-      }
-      return x509Certificates.get(0);
-    }
-
     /**
      * Returns the X.509 certificate chain header parameter contains the X.509 public key
      * certificate or certificate chain corresponding to the key used to digitally sign the JWS or
@@ -303,24 +288,6 @@ public final List<String> getX509Certificates() {
       return new ArrayList<>(x509Certificates);
     }
 
-    /**
-     * Sets the X.509 certificate chain header parameter contains the X.509 public key certificate
-     * corresponding to the key used to digitally sign the JWS or {@code null} for none.
-     *
-     * <p>Overriding is only supported for the purpose of calling the super implementation and
-     * changing the return type, but nothing else.
-     *
-     * <p>@deprecated Since release 1.19.1, replaced by {@link #setX509Certificates(List
-     * x509Certificates)}.
-     */
-    @Deprecated
-    public Header setX509Certificate(String x509Certificate) {
-      ArrayList<String> x509Certificates = new ArrayList<String>();
-      x509Certificates.add(x509Certificate);
-      this.x509Certificates = x509Certificates;
-      return this;
-    }
-
     /**
      * Sets the X.509 certificate chain header parameter contains the X.509 public key certificate
      * or certificate chain corresponding to the key used to digitally sign the JWS or {@code null}