Normalize The HTTP Method When Building The Route Table

[stevehu]

Fixes #175.

Stacked on #177. The base branch is #177, not master, because the #175 fix cannot be tested without the seam #177 introduces — LambdaProxyMiddleware's only constructor builds a real LambdaAsyncClient. Please merge #177 first; GitHub will retarget this to master automatically. The diff shown here is only this change.

The bug

The route table was keyed by the raw method from configuration, while lookups used the lower cased request method:

var method = exchange.getRequest().getHttpMethod().toLowerCase();  // lookup: "get"
var method = endpoint[1];                                          // registration: "GET"

So /v1/pets@GET registered a route that no request could ever reach. Before #174 this surfaced as an NPE; since #174 it fails as a clean ERR10086, which is correct handling for a routing miss but makes the misconfiguration silent — the route is simply dead.

Changes

• normalizeMethod applied on both registration and lookup, so the two sides cannot drift again.
• Locale.ROOT rather than the default locale. OPTIONS contains an I, so under a Turkish default locale toLowerCase() yields optıons with a dotless i and the route breaks. This is why the helper exists rather than just adding .toLowerCase() at the registration site.
• Split on the last @ instead of every @, so a path containing the separator still parses.
• Malformed keys are skipped with a logged error instead of throwing ArrayIndexOutOfBoundsException during construction. A single bad entry taking down every invocation of the proxy seemed the worse failure mode, but say the word if you would rather fail fast at startup.
• Dropped the redundant put — computeIfAbsent already inserts and the matcher is mutated in place.

Verification

The five new tests were run against the pre-fix source and all fail with exactly the reported symptoms:

testUpperCaseConfiguredMethodStillRoutes:104            expected: <PetsGetFunction> but was: <null>
testMixedCaseConfiguredMethodStillRoutes:110            expected: <PetsDeleteFunction> but was: <null>
testUpperCaseConfiguredMethodIsReachableByAnUpperCaseRequest:122
                                                        expected: <PetsPostFunction> but was: <null>
testMalformedConfigurationKeysAreSkippedWithoutFailingStartup:144
                            ArrayIndexOutOfBoundsException: Index 1 out of bounds for length 1
testPathContainingSeparatorIsSplitOnTheLastSeparator:132 » Runtime

With the fix: Tests run: 84, Failures: 0, Errors: 0, Skipped: 4 — 79 from #177, 5 added. BUILD SUCCESS, git diff --check clean.

Compatibility

Existing all-lowercase configurations are unaffected — values.yml in the test resources already uses lowercase, and the full suite passes unchanged. Configurations that currently use upper or mixed case will start routing where they previously returned ERR10086. That is the intent of the fix, but it is a behaviour change worth calling out.

🤖 Generated with Claude Code

[stevehu]

The patch consistently normalizes configured and incoming HTTP methods with Locale.ROOT, safely parses endpoint keys using the final separator, and adds targeted regression coverage. No actionable correctness issue was identified.