Examples-GroupDocs.Metadata-for-Java
// initialize PptFormat
PptFormat pptFormat = new PptFormat(Common.mapSourceFilePath(path));
// get document properties
PptMetadata properties = pptFormat.getDocumentProperties();
// update built-in properties
properties.setAuthor("test author");
properties.setSubject("test subject");
properties.setManager("test manager");
// commit changes
pptFormat.save(Common.mapDestinationFilePath(outputPath));