Values_2.MappingEntrySourceDefines a mapping.
type nonrec t = {sourceTable : Values_1.TableName.t option;The name of the source table.
*)sourcePath : SchemaPathString.t option;The source path.
*)sourceType : Values_1.FieldType.t option;The source type.
*)targetTable : Values_1.TableName.t option;The target table.
*)targetPath : SchemaPathString.t option;The target path.
*)targetType : Values_1.FieldType.t option;The target type.
*)}