/usr/include/KDE/KTextEditor/ is in kdelibs5-dev 4:4.8.2-0ubuntu1.
This file is owned by root:root, with mode 0o755.
..
/usr/include/KDE/KTextEditor/Attribute
/usr/include/KDE/KTextEditor/CodeCompletionInterface
/usr/include/KDE/KTextEditor/CodeCompletionModel
/usr/include/KDE/KTextEditor/CodeCompletionModelControllerInterface
/usr/include/KDE/KTextEditor/Command
/usr/include/KDE/KTextEditor/CommandExtension
/usr/include/KDE/KTextEditor/CommandInterface
/usr/include/KDE/KTextEditor/ConfigInterface
/usr/include/KDE/KTextEditor/ConfigPage
/usr/include/KDE/KTextEditor/ContainerInterface
/usr/include/KDE/KTextEditor/Cursor
/usr/include/KDE/KTextEditor/Document
/usr/include/KDE/KTextEditor/Editor
/usr/include/KDE/KTextEditor/EditorChooser
/usr/include/KDE/KTextEditor/Factory
/usr/include/KDE/KTextEditor/HighlightInterface
/usr/include/KDE/KTextEditor/MarkInterface
/usr/include/KDE/KTextEditor/ModificationInterface
/usr/include/KDE/KTextEditor/MovingCursor
/usr/include/KDE/KTextEditor/MovingInterface
/usr/include/KDE/KTextEditor/MovingRange
/usr/include/KDE/KTextEditor/ParameterizedSessionConfigInterface
/usr/include/KDE/KTextEditor/Plugin
/usr/include/KDE/KTextEditor/Range
/usr/include/KDE/KTextEditor/SearchInterface
/usr/include/KDE/KTextEditor/SessionConfigInterface
/usr/include/KDE/KTextEditor/SmartCursor
/usr/include/KDE/KTextEditor/SmartCursorNotifier
/usr/include/KDE/KTextEditor/SmartCursorWatcher
/usr/include/KDE/KTextEditor/SmartInterface
/usr/include/KDE/KTextEditor/SmartRange
/usr/include/KDE/KTextEditor/SmartRangeNotifier
/usr/include/KDE/KTextEditor/SmartRangeWatcher
/usr/include/KDE/KTextEditor/TemplateInterface
/usr/include/KDE/KTextEditor/TemplateInterface2
/usr/include/KDE/KTextEditor/TextHintInterface
/usr/include/KDE/KTextEditor/VariableInterface
/usr/include/KDE/KTextEditor/View