Move off deprecated Base64Utils.

Closes gh-797

Author: mp911de

spring-vault-core/src/main/java/org/springframework/vault/core/VaultTransitTemplate.java

@@ -15,6 +15,14 @@
  */
 package org.springframework.vault.core;
 
+import java.util.ArrayList;
+import java.util.Base64;
+import java.util.Collections;
+import java.util.LinkedHashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Objects;
+
 import com.fasterxml.jackson.annotation.JsonProperty;
 import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
@@ -40,14 +48,6 @@
 import org.springframework.vault.support.VaultTransitKeyConfiguration;
 import org.springframework.vault.support.VaultTransitKeyCreationRequest;
 
-import java.util.ArrayList;
-import java.util.Base64;
-import java.util.Collections;
-import java.util.LinkedHashMap;
-import java.util.List;
-import java.util.Map;
-import java.util.Objects;
-
 /**
  * Default implementation of {@link VaultTransitOperations}.
  *