fix cargo doc

Author: xudong963

datafusion/physical-plan/src/aggregates/group_values/mod.rs

@@ -15,7 +15,7 @@
 // specific language governing permissions and limitations
 // under the License.
 
-//! [`GroupValues`] trait for storing and interning group keys
+//! `GroupValues` trait for storing and interning group keys
 
 use arrow::array::types::{
     Date32Type, Date64Type, Decimal128Type, Time32MillisecondType, Time32SecondType,
@@ -84,7 +84,7 @@ mod null_builder;
 /// Each distinct group in a hash aggregation is identified by a unique group id
 /// (usize) which is assigned by instances of this trait. Group ids are
 /// continuous without gaps, starting from 0.
-pub trait GroupValues: Send {
+pub(crate) trait GroupValues: Send {
     /// Calculates the group id for each input row of `cols`, assigning new
     /// group ids as necessary.
     ///
@@ -127,7 +127,7 @@ pub trait GroupValues: Send {
 ///
 /// [`GroupColumn`]:  crate::aggregates::group_values::multi_group_by::GroupColumn
 ///
-pub fn new_group_values(
+pub(crate) fn new_group_values(
     schema: SchemaRef,
     group_ordering: &GroupOrdering,
 ) -> Result<Box<dyn GroupValues>> {