Make MapFieldNames public (#2118) (#2134)
diff --git a/arrow/src/array/builder/mod.rs b/arrow/src/array/builder/mod.rs
index a5b7f1e..f97ff4c 100644
--- a/arrow/src/array/builder/mod.rs
+++ b/arrow/src/array/builder/mod.rs
@@ -52,7 +52,7 @@
pub use generic_binary_builder::GenericBinaryBuilder;
pub use generic_list_builder::GenericListBuilder;
pub use generic_string_builder::GenericStringBuilder;
-pub use map_builder::MapBuilder;
+pub use map_builder::{MapBuilder, MapFieldNames};
pub use primitive_builder::PrimitiveBuilder;
pub use primitive_dictionary_builder::PrimitiveDictionaryBuilder;
pub use string_dictionary_builder::StringDictionaryBuilder;