SPI permitting new classpaths to be constructed and registered.

{@link org.netbeans.spi.java.classpath.ClassPathProvider}s can be registered to default lookup in order to associate information about classpaths with files. For example, a Java-oriented project type would normally indicate that its Java sources have a certain classpath associated with them.
For a source file the ClassPathProvider has to return a {@link org.netbeans.api.java.classpath.ClassPath} of the following ClassPath types:

it may also return a ClassPath of type ClassPath.EXEC pointing to the build output folder.
For build output the ClassPathProvider has to return a ClassPath of the following types:

{@link org.netbeans.spi.java.classpath.ClassPathFactory} may be used to create new {@link org.netbeans.api.java.classpath.ClassPath} instances.