The issue arises because the stream.showText() method in the PDFBox library automatically applies encoding to the text. This encoding replaces the standard space character (U+0020) with encoded glyphs. Since wordSpacing (Tw) only affects the spacing of the actual U+0020 space character, it has no effect when encoded glyphs are used.

To address this and properly apply wordSpacing, you can manually split the text at spaces and insert them into the content stream separately. This allows the wordSpacing parameter to function as intended.

Here is the corrected version of your code:`try (PDPageContentStream stream = new PDPageContentStream(
pdf,
page,
PDPageContentStream.AppendMode.APPEND,
false,
true)) {

stream.saveGraphicsState();
stream.setFont(font, fontSize);
stream.setNonStrokingColor(color);
stream.beginText();
stream.newLineAtOffset(100, 100);
stream.setWordSpacing(50);

// Split text at spaces and write each part with spacing applied
String text = "HELLO WORLD";
String[] words = text.split(" ");
for (int i = 0; i < words.length; i++) {
    stream.showText(words[i]); // Add the word
    if (i < words.length - 1) {
        stream.showText(" "); // Add a space to let wordSpacing apply
    }
}

stream.endText();
stream.restoreGraphicsState();

}
`