[reginaldalfret]

Problem

In PR #4017, VALID_ALPHA_PHONE_PATTERN ((?:.?[A-Za-z]){3}.) was replaced with hasAtLeastThreeAlphaChars() in PhoneNumberUtil.isAlphaNumber() because the non-greedy regex causes recursive stack frame evaluation in java.util.regex, resulting in StackOverflowError on long numeric input strings.

However, PhoneNumberUtil.normalize(StringBuilder) still called:
java Matcher m = VALID_ALPHA_PHONE_PATTERN.matcher(number); if (m.matches()) {
leaving
ormalize() vulnerable to the exact same StackOverflowError when called with long numeric inputs (e.g. ~1,684+ digits), and leaving VALID_ALPHA_PHONE_PATTERN in the codebase solely for that one call.

Solution

1. Replace VALID_ALPHA_PHONE_PATTERN.matcher(number).matches() with hasAtLeastThreeAlphaChars(number) in PhoneNumberUtil.normalize(StringBuilder).
2. Delete the now-unused VALID_ALPHA_PHONE_PATTERN constant from PhoneNumberUtil.java.
3. Add regression test estNormaliseLongNumericInputDoesNotThrow in PhoneNumberUtilTest.java.
4. Update pending_code_changes.txt.

Verification

• Added estNormaliseLongNumericInputDoesNotThrow testing normalization of 5,000 digits without StackOverflowError.
• Ran mvn -pl java/libphonenumber test: all 285 tests passed with 0 failures, 0 errors.