Solved SpotBugs issue regarding byte array references. Let's clone all the things!

Author: bbottema

modules/core-module/src/main/java/org/simplejavamail/api/email/config/DkimConfig.java

@@ -54,12 +54,20 @@ public class DkimConfig implements Serializable {
 	@Nullable private final Set<String> excludedHeadersFromDkimDefaultSigningList;
 
 	DkimConfig(byte[] dkimPrivateKeyData, String dkimSigningDomain, String dkimSelector, @Nullable Set<String> excludedHeadersFromDkimDefaultSigningList) {
-		this.dkimPrivateKeyData = dkimPrivateKeyData;
+		this.dkimPrivateKeyData = dkimPrivateKeyData.clone();
 		this.dkimSigningDomain = dkimSigningDomain;
 		this.dkimSelector = dkimSelector;
 		this.excludedHeadersFromDkimDefaultSigningList = excludedHeadersFromDkimDefaultSigningList;
 	}
 
+	/**
+	 * @see EmailPopulatingBuilder#signWithDomainKey(DkimConfig)
+	 * @see EmailPopulatingBuilder#signWithDomainKey(byte[], String, String, Set)
+	 */
+	public byte[] getDkimPrivateKeyData() {
+		return dkimPrivateKeyData.clone();
+	}
+
 	public static DkimConfigBuilder builder() {
 		return new DkimConfigBuilder();
 	}