Singular vs plural in type names

[t2gran]

I vote for using singular in all package and type names, unless it is a collection of something. Here are some examples (Here is about top 50% of the OTP classes matching class \w+s[\p{Lu} ]):

• AreaStopToVertexMapper not AreaStopsToVerticesMapper
• BikesAllowedMapper not BikeAllowedMapper
• ConsolidatedStopNameDecorator not DecorateConsolidatedStopNames
• EmissionSomeThing, not EmissionsSomeThing
• EnumTypeDefinitions, not EnumTypes (Transmodel API)
• FareConfiguration, not FaresConfiguration
• GeofencingZoneNnn, not GeofencingZonesNnn
• Gram not Grams
• GtfsFareV2Service, not GtfsFaresV2Service
• Issue(Store|Repository|Service) not Issues ...
• ItineraryHelper not ItinerariesHelper
• ItineraryListFilter not ItinerarysFilter
• ItineraryFareDecorator, not ItineraryFaresDecorator
• ObjectMapperFactory, not ObjectMappers
• PathCollectionMerger not MergePaths
• UnitUtils not Units (This is deprecated and should be replaced by value objects)

Unsure about these:

• CombinedInterlinedLegs
• SomeThingPreferences
• SomeThingUtils
• TransmodelScalars, maybe TransmodelScalarDefinitions (keeping the s, but improving the name)

Not change these:

• APIEndpoints (Could use APIEndpointService)

• GraphQL Query types (GraphQLAccessibilityPreferencesInput, ...)

• IssueColors - List of colors and utility functions

• NumOfItinerariesFilter - The filter is named after the numOfItineraries request parameter.

• OpeningHours

• OtpFileNames - List of config file names, could be OtpConfigFileNames

• RemoveOtherThanSameLegsMaxGeneralizedCost - Here the meaning changes dramatically. The meaning of OtherThanSameLeg is different from OtherThanSameLegs.

• StopTimes(Nnn)

• UpdaterStatusResource

• Package api is the framework, while apis contain the collection of all official OTP APIs (except Sandbox)

Using suffixes like List, Info, Service, Repository, Factory, Definitions, and Utils is ok, and can in some cases make the type read more easy and at the same time avoid the s.

Note! In many Java libraries the suffix s is used for utility classes, but we uses Utils (TimeUtils)

Originally posted by @t2gran in #6558 (comment)