-nosubstitution

Setting this to true disables package substitution globally (default is false). That means, that bnd does not calculate Import-Package references for packages exported by the current bundle.

Example: -nosubstitution=true
Values: true,false
Pattern: true|false|TRUE|FALSE

See Subsitution to learn more about package Substition (a key aspect of OSGi allowing that a package can be both exported and imported).

Note, that package substitution behaviour is enabled by default in bnd for backward-compatibilty. But recommended to disable for most cases these days via -nosubstitution:true.

Example

-nosubstitution:true
-exportcontents: *
Import-Package: *

This ensures that no Import-Package is calculated for any package in Export-Package. This is equivalent to Export-Package: *;-noimport:=true or -exportcontents: *;-noimport:=true.

The advantage is that -nosubstitution:true is a global switch, thus a developer cannot forget to add -noimport:=true in case of a more fine-grained Export-Package declaration with multiple packages.

Why is it useful?

It is useful for library authors who never want to have any exported packages in Import-Package. Often, library authors who are just using bnd to generate OSGi metadata in their build scripts (e.g. via maven or gradle plugins) but are otherwise unfamiliar with bnd and OSGi, need a simple way to disable this substitution behavior, because it can lead to surprising resolution results (or failures) after deployment (because other bundles providing the same package are pulled in). This is often undesirable in a pure “library” use-case.

This instruction helps making bnd / OSGi adoption easier for library projects just wanting to provide OSGi metadata.