[Unicode letters don;'t display in PDF]

I am using DejaVu Sans to export & display a unicode PDF report. The PDF looks fine when previewed from within JasperSoft Studio but when exported through JasperReports the unicode text fields are blank & I get the following warning:

net.sf.jasperreports.engine.export.PdfGlyphRenderer determinePatchedItext

WARNING: Unpatched iText found, cannot use glyph rendering

 

When exporting to HTML or excel, unicode letters are displayed correctly. DejaVu Sans is already available to the JVM as I am not using any custom or 3rd pary font, kindly advice on a solution.

 

I am using JasperSoft Studio 6.3.1 on CentOS 7.

 

Thanks.