SPI 
Package Description
org.eclipse.aether.spi.connector
The contract to access artifacts/metadata in remote repositories.
org.eclipse.aether.spi.connector.checksum
The support infrastructure for repository connectors to apply checksum policies when validating the integrity of downloaded files.
org.eclipse.aether.spi.connector.layout
The contract to locate URI-based resources using custom repository layouts.
org.eclipse.aether.spi.connector.transport
The contract to download/upload URI-based resources using custom transport protocols.
org.eclipse.aether.spi.io
I/O related support infrastructure for components.
org.eclipse.aether.spi.localrepo
The contract for custom local repository implementations.
org.eclipse.aether.spi.locator
A lightweight service locator infrastructure to help components acquire dependent components.
org.eclipse.aether.spi.log
A simple logging infrastructure for diagnostic messages.