in bijection-core/src/main/java/com/twitter/bijection/codec/BaseNCodec.java [413:421]
public boolean isInAlphabet(final byte[] arrayOctet, final boolean allowWSPad) {
for (int i = 0; i < arrayOctet.length; i++) {
if (!isInAlphabet(arrayOctet[i]) &&
(!allowWSPad || (arrayOctet[i] != PAD) && !isWhiteSpace(arrayOctet[i]))) {
return false;
}
}
return true;
}