When the ProtocolResolver SPI was introduced in Spring Framework 4.3,
support for protocol resolvers was added in DefaultResourceLoader's
getResource() implementation; however, GenericApplicationContext's
overridden getResource() implementation was not updated accordingly.
Prior to this commit, if a GenericApplicationContext was configured
with a custom ResourceLoader, registered protocol resolvers were
ignored.
This commit ensures that protocol resolvers are honored in
GenericApplicationContext even if a custom ResourceLoader is used.
Closes gh-28703
9868c28c73