ensure keystore source and wallet model is always filled in

src/main/java/com/sparrowwallet/drongo/wallet/Keystore.java

@@ -66,7 +66,7 @@ public class Keystore {
     }
 
     public boolean isValid() {
-        if(label == null || keyDerivation == null || extendedPublicKey == null) {
+        if(label == null || source == null || walletModel == null || keyDerivation == null || extendedPublicKey == null) {
             return false;
         }
 
@@ -85,6 +85,8 @@ public class Keystore {
 
     public Keystore copy() {
         Keystore copy = new Keystore(label);
+        copy.setSource(source);
+        copy.setWalletModel(walletModel);
         if(keyDerivation != null) {
             copy.setKeyDerivation(keyDerivation.copy());
         }

src/main/java/com/sparrowwallet/drongo/wallet/WalletModel.java

@@ -15,6 +15,16 @@ public enum WalletModel {
         return this.toString();
     }
 
+    public static WalletModel fromType(String type) {
+        for(WalletModel model : values()) {
+            if(model.getType().equals(type)) {
+                return model;
+            }
+        }
+
+        return null;
+    }
+
     public String toDisplayString() {
         String line = this.toString().toLowerCase();
         String[] words = line.split("_");