docs: private FixedStringSearchInterpolator mainProjectInterpolator(MavenProject mainProject)
      {
          if (mainProject != null) {
              // 5
              return FixedStringSearchInterpolator.create(
                  new org.codehaus.plexus.interpolation.fixed.PrefixedObjectValueSource(
                      InterpolationConstants.PROJECT_PREFIXES, mainProject, true ),
  
                  // 6
                  new org.codehaus.plexus.interpolation.fixed.PrefixedPropertiesValueSource(
                      InterpolationConstants.PROJECT_PROPERTIES_PREFIXES, mainProject.getProperties(), true ) );
          }
          else {
              return FixedStringSearchInterpolator.empty();
          }
      }