Mapper not showing target schema for my custom snap

Your Snap needs to implement the InputSchemaProvider interface in order for the Mapper to show any target schema. An example implementation that should show two fields, ‘field1’ and ‘field2’, would be:

    @Override
    public void defineInputSchema(SchemaProvider provider) {
        for (String inputViewName : provider.getRegisteredViewNames()) {
            Schema field1Schema = provider.createSchema(SnapType.STRING, "field1");
            Schema field2Schema = provider.createSchema(SnapType.STRING, "field2");
            provider.getSchemaBuilder(inputViewName)
                    .withChildSchema(field1Schema)
                    .withChildSchema(field2Schema)
                    .build();
        }
    }