fix for Scala 2.11

Author: kushti

ergo-wallet/src/main/java/org/ergoplatform/wallet/interface4j/crypto/ErgoUnsafeProver.java

@@ -2,7 +2,7 @@
 
 import org.ergoplatform.ErgoLikeTransaction;
 import org.ergoplatform.UnsignedErgoLikeTransaction;
-import scala.collection.JavaConverters;
+import scala.collection.JavaConversions;
 import sigmastate.basics.DLogProtocol;
 import java.util.Map;
 
@@ -26,7 +26,8 @@ public ErgoLikeTransaction prove(UnsignedErgoLikeTransaction unsignedTx, DLogPro
      * @return signed transaction
      */
     public ErgoLikeTransaction prove(UnsignedErgoLikeTransaction unsignedTx, Map<String, DLogProtocol.DLogProverInput> sks) {
-        return org.ergoplatform.wallet.interpreter.ErgoUnsafeProver.prove(unsignedTx, JavaConverters.mapAsScalaMap(sks));
+        // JavaConversions used to support Scala 2.11
+        return org.ergoplatform.wallet.interpreter.ErgoUnsafeProver.prove(unsignedTx, JavaConversions.mapAsScalaMap(sks));
     }
 
 }