[fly1d]

Fixes #885.

After a multiline string, an invalid URL include on line 5 is reported as line 2. ConfigParser builds semantic errors from a counter that only sees newline nodes, missing newlines embedded in quoted tokens.

Use the offending include or field node's first positioned token for the error origin, falling back to the existing counter when no token has a location. This also handles preceding multiline keys, without changing tokenizer or value/object/array origins. Existing messages and causes are preserved.

Validation on macOS arm64:

• Temurin 11, sbt 1.11.2: test doc passed, with 607 tests and successful API documentation generation.
• Three new test methods cover 11 inputs. With pristine production code, the two multiline regressions fail and the escaped-newline control passes; the fixed ConfParserTest passes all 46 tests.
• Two separate public API programs on JDK 17 check 16 scenarios, including CRLF, concatenation, nested values, multiline keys, file/custom origins and an unresolved include inside a list. The original code fails 11 scenarios; the fix passes all 16.

Related work in the Scala port: ekrich/sconfig#641. This PR is limited to the Java parser and its tests. Java 8 and Linux/Windows execution were not tested locally.

[lightbend-cla-validator]

Hi @fly1d,

Thank you for your contribution! We really value the time you've taken to put this together.

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