[wozhenbang2004]

A client targeting HTTP://host currently fails with target values must be absolute, even though the URI has an HTTP scheme. The same check affects HTTPS and mixed-case schemes. Fixing the template check alone still lets HardCodedTarget replace a per-request URI with the configured default target, while EmptyTarget continues to reject it.

Use a case-insensitive prefix check in UriUtils.isAbsolute, and share it with both target implementations. The scheme spelling is preserved in the request URL.

Regression coverage includes real requests to MockWebServer through a configured target, a per-request URI override, and an empty target, with lowercase, uppercase, and mixed-case HTTP schemes. Template tests also cover uppercase and mixed-case HTTP/HTTPS targets with paths, queries, and fragments, and ensure that absolute URLs are rejected by the relative-URI setter.

Validation:

• New regressions fail on the original implementation and pass with the fix.
• Core clean install with -Pdev -pl core -am, using JDK 8 for production sources and JDK 25 for tests: 783 tests, no failures or errors, 4 skips. Mockito was supplied as a premain Java agent for this environment.
• License checks, code-format validation, module packaging, and binary compatibility checks pass.

[velo]

Checked against master: isAbsolute, HardCodedTarget and EmptyTarget now share one case-insensitive check, and the tests fail on master and pass here. Nit, not blocking: like the old check, this is a prefix match, so a relative uri() literal that starts with 'HTTP' without a leading slash is now rejected as absolute, the same way a lowercase 'http' one already was. Matching 'http://' or 'https://' would be tighter, but that can come in a follow-up.

[velo]

Approved, and auto-merge is enabled. It now conflicts with master, but only in CHANGELOG.md, because master already has a ### Version 13.18 section. Could you merge or rebase master and move your entry under that existing heading? (#3633 also adds to RequestTemplateTest, so if it lands first, you may need another quick rebase.)

[velo]

Merged master; CHANGELOG.md was removed from the repo so the entry was dropped.