Generation region/service metadata

[spfink]

Introduces two new modules, codegen-lite and codegen-lite-maven-plugin in order to be able to generate region and service metadata for the regions module.

Could also refactor codegen-lite into codegen-core and move the core non-service related codegen files to this module

@Generated("software.amazon.awssdk:codegen")
@SdkPublicApi
public final class Batch implements ServiceMetadata {
    private static final String ENDPOINT_PREFIX = "batch";

    private static final Map<String, String> REGION_OVERRIDDEN_ENDPOINTS = new HashMap();

    private static final List<Region> REGIONS = Collections.unmodifiableList(Arrays.asList(Region.AP_NORTHEAST_1,
            Region.AP_NORTHEAST_2, Region.AP_SOUTH_1, Region.AP_SOUTHEAST_1, Region.AP_SOUTHEAST_2, Region.CA_CENTRAL_1,
            Region.EU_CENTRAL_1, Region.EU_WEST_1, Region.EU_WEST_2, Region.EU_WEST_3, Region.SA_EAST_1, Region.US_EAST_1,
            Region.US_EAST_2, Region.US_WEST_1, Region.US_WEST_2));

    private static final Map<String, String> SIGNING_REGION_OVERRIDES = new HashMap();

    @Override
    public List<Region> regions() {
        return REGIONS;
    }

    @Override
    public URI endpointFor(Region region) {
        return URI.create(REGION_OVERRIDDEN_ENDPOINTS.getOrDefault(region.id(), computeEndpoint(ENDPOINT_PREFIX, region)));
    }

    @Override
    public Region signingRegion(Region region) {
        return Region.of(SIGNING_REGION_OVERRIDES.getOrDefault(region.id(), region.id()));
    }
}

@Generated("software.amazon.awssdk:codegen")
@SdkPublicApi
public final class UsEast1 implements RegionMetadata {
    private static final String ID = "us-east-1";

    private static final String DOMAIN = "amazonaws.com";

    private static final String NAME = "US East (N. Virginia)";

    private static final String PARTITION = "aws";

    public String name() {
        return NAME;
    }

    public String domain() {
        return DOMAIN;
    }

    public String id() {
        return ID;
    }

    public String partition() {
        return PARTITION;
    }
}

[shorea]

Can you add those diff tests for the new generated classes? Also do we still support custom endpoint files at runtime?

[shorea]

Could we rename the generated metadata file to something like BatchServiceMetadata?

[shorea]

Can the region class itself be generated?

[spfink]

Will add diff tests.

Fine with adding ServiceMetadata suffix.

Can switch Region to be generated as well.

[shorea]

can you explain what this does? not quite getting it.

[spfink]

This comment is slightly incorrect as I just copied it from the other but it's just the configuration for running the codegen-lite-maven-plugin. It's exactly copied from the pom.xml of the services module just with the "lite" version.

[shorea]

Can we use ImmutableMap.Builder here? I feel like that would cut down on the verbosity.

[spfink]

Can do.

[shorea]

Can we keep the docs in the generated version?

[spfink]

Ah, yes. This was just a miss.

[shorea]

Should we keep this an interface if we decide to support runtime discovery later on?

[spfink]

Makes sense. Will do.