Added mapping from Bytearray to String

Author: Henge9

modules/swagger-codegen/src/main/java/io/swagger/codegen/languages/DartClientCodegen.java

@@ -100,6 +100,7 @@ public DartClientCodegen() {
         //TODO binary should be mapped to byte array
         // mapped to String as a workaround
         typeMapping.put("binary", "String");
+        typeMapping.put("ByteArray", "String");
 
         cliOptions.add(new CliOption(BROWSER_CLIENT, "Is the client browser based"));
         cliOptions.add(new CliOption(PUB_NAME, "Name in generated pubspec"));