Mail Task Non English Character Issues

In Camunda, ‘Mail Task’ the issue is all the non english characters are coming in as ‘?’ in the mail subject/body.
We tried with the following ‘Charset’ property values: Default, UTF-8 &
ISO-8859-1 (this was not needed though) but nothing worked.

But when we give unicode characters it worked for mail body, but subject line didn’t work.

We are setting it from : CamundaField.class.
CamundaField prop = model.newInstance(CamundaField.class);
prop.setCamundaStringValue(value); -> where value is character set.

Need your input for this.