function updateFeatureStruct(shaderBuilder) {
  shaderBuilder.addStructField(
    SelectedFeatureIdPipelineStage.STRUCT_ID_SELECTED_FEATURE,
    "int",
    "id",
  );

  shaderBuilder.addStructField(
    SelectedFeatureIdPipelineStage.STRUCT_ID_SELECTED_FEATURE,
    "vec2",
    "st",
  );

  shaderBuilder.addStructField(
    SelectedFeatureIdPipelineStage.STRUCT_ID_SELECTED_FEATURE,
    "vec4",
    "color",
  );
}
Populate the "SelectedFeature" struct in the shaders that holds information about the "active" (used for picking/styling) feature.
The struct is always added to the shader by the GeometryPipelineStage (required for compilation). The SelectedFeature struct looks
as follows:

struct SelectedFeature {
  int id;
  vec2 st;
  vec4 color;
}

@private