private GTheme readZipTheme() throws IOException {
		try (ZipFile zipFile = new ZipFile(file)) {
			Enumeration<? extends ZipEntry> entries = zipFile.entries();
			while (entries.hasMoreElements()) {
				ZipEntry entry = entries.nextElement();
				String name = entry.getName();
				try (InputStream is = zipFile.getInputStream(entry)) {
					if (name.endsWith(".theme")) {
						processThemeData(name, is);
					}
					else {
						processIconFile(name, is);
					}
				}
			}
		}
		return theme;
	}
Assumes the file is a theme file and reads it.
Ghidra/Framework/Gui/src/main/java/generic/theme/ThemeReader.java