Revert "Removed getWalletTransactions() synchronization. Again, can be re-added later."

This reverts commit 70c864bc2f.

src/main/java/org/qortal/crosschain/Bitcoiny.java

@@ -342,6 +342,7 @@ public abstract class Bitcoiny implements ForeignBlockchain {
 	}
 
 	public List<SimpleTransaction> getWalletTransactions(String key58) throws ForeignBlockchainException {
+		synchronized (this) {
 			Context.propagate(bitcoinjContext);
 
 			Wallet wallet = walletFromDeterministicKey58(key58);
@@ -408,6 +409,7 @@ public abstract class Bitcoiny implements ForeignBlockchain {
 					.map(t -> convertToSimpleTransaction(t, keySet))
 					.sorted(newestTimestampFirstComparator).collect(Collectors.toList());
 		}
+	}
 
 	protected SimpleTransaction convertToSimpleTransaction(BitcoinyTransaction t, Set<String> keySet) {
 		long amount = 0;