[jdt-core-dev] Unused imports compiler warning

["Philippe Mulet" <Philippe_Mulet@xxxxxxx>]

Through the compiler preferences, you can enable a warning for signalling
unused import statements.

Though leaving these in doesn't impact the generated classfiles, they
introduce extra dependencies which could cause
your code to be rejected later on, if the imported code was becoming
unavailable.

Also, extra dependencies will also slow down the incremental image builder,
so you might just want to make sure you don't have any left.

Before checking, JDT/Core had about 600 unused imports (mostly due to
codeassist automatically adding imports).