14213 Logic to determine which LineString matches direction

[mdorford]

The logic to determine which LineString(s) to return is moved into GraphHopper.
Some nice advantages are:

1. 'Both directions' is handled now.
2. 'Unknown' is handled much better.
3. Determination of direction is more accurate because it is based on the furthest-from-start endpoint of each LineString rather than end-to-start of one LineString. This will be much more acccurate in certain, unusual circumstances such as curvy mountain roads.
4. Processing speed is faster because the cardinal directions no longer calculate bearing.

[payneBrandon]

question: are we using all the sub ".*" options in here to warrant importing them all?

[mdorford]

The change in the imports was done by IntelliJ itself. I don't know where its threshold is. Maybe once it was using four or five imports from the same library it just automatically switches to import them all. Maybe it uses some more sophisticated way to decide or maybe it really needed them.

[mdorford]

I cleanup up the imports.

[Copilot]

Pull Request Overview

This PR adds direction-based filtering to the buffer endpoint so that returned LineStrings can be limited to a requested compass direction.

• Introduces a Direction enum and direction query parameter
• Implements filterByDirection(...) with cardinal and diagonal logic
• Refactors imports and delegates to bearing-based selection for non-cardinal directions

Comments suppressed due to low confidence (3)

web-bundle/src/main/java/com/graphhopper/resources/BufferResource.java:92

• Parsing the direction parameter with valueOf may throw IllegalArgumentException for invalid input. Consider validating the input or catching the exception and returning a 400 Bad Request with a clear error message.

Direction directionEnum = Direction.valueOf(directionUpperCase);

web-bundle/src/main/java/com/graphhopper/resources/BufferResource.java:116

• The new direction-filtering logic covers many branches (cardinal, diagonal, both/unknown). Please add unit tests for each direction and edge cases (empty list, BOTH, UNKNOWN).

private List<LineString> filterByDirection(List<LineString> lineStrings, Boolean buildUpstream, Direction directionEnum) {

web-bundle/src/main/java/com/graphhopper/resources/BufferResource.java:78

• The new direction parameter is not documented in the Javadoc or REST API docs. Please update the endpoint documentation to list valid values and describe the filtering behavior.

@QueryParam("direction") @DefaultValue("unknown") String direction,

[payneBrandon]

Couple questions