in remote/src/main/java/com/spotify/metrics/remote/Sharder.java [47:55]
public static String httpHeaderEscape(String key) {
StringBuilder res = new StringBuilder();
for (char c : key.toCharArray()) {
if (((c >= 'a' && c <= 'z')) || ((c >= 'A' && c <= 'Z'))) {
res.append(c);
}
}
return res.toString();
}