Introduce a api that uses minecraft internal DefinedStructureManager (spigot name) or TemplateManager (mcp name) to be able to load and save structures.
structures are similar so schematics, they are nbt files that save blocks and entities, but it is the official format for doing so.
A api for bukkit/spigot would wrap the nms classes (DefinedStructureManager, DefinedStructure, EnumBlockMirror, EnumBlockRotation etc) and provide all necessary methods so load and save structures with all available options. (saveing with and without entities, the author and a name, loading with or without entities, rotated or mirrored and potentially others that I have missed)
I threw together a quick implementation of this here (https://www.spigotmc.org/threads/structure-util-nms-schematics.199250 and https://gist.github.com/MiniDigger/ce2b0b0446d53d3bb94f24f1c708c657)

if this feature will be accepted I am willing to write a api proposal and a PR.