Convert byte[] -> bytes32 and fail on unknown classes instead of sile…

…ntly encode to byte[0]

(cherry picked from commit 5c02de2)

ethereumj-core/src/main/java/org/ethereum/solidity/SolidityType.java

@@ -289,9 +289,14 @@ public byte[] encode(Object value) {
                 byte[] bytes = ((String) value).getBytes(StandardCharsets.UTF_8);
                 System.arraycopy(bytes, 0, ret, 0, bytes.length);
                 return ret;
+            } else if (value instanceof byte[]) {
+                byte[] bytes = (byte[]) value;
+                byte[] ret = new byte[32];
+                System.arraycopy(bytes, 0, ret, 32 - bytes.length, bytes.length);
+                return ret;
             }
 
-            return new byte[0];
+            throw new RuntimeException("Can't encode java type " + value.getClass() + " to bytes32");
         }
 
         @Override