@Override
    public void filter(Metadata metadata) throws TikaException {
        for (String n : metadata.names()) {
            String[] vals = metadata.getValues(n);
            metadata.remove(n);
            for (String val : vals) {
                metadata.add(n, val.toUpperCase(Locale.US));
            }
        }
    }
Mock Filter for testing uppercasing of all values
tika-core/src/test/java/org/apache/tika/metadata/filter/MockUpperCaseFilter.java