insert custom block on draftJS

    insertMedia(type, src, cb) {
        let editorState = this.state.editorState
        let contentState = editorState.getCurrentContent();
        let selectionState = editorState.getSelection();

        let afterRemoval = Modifier.removeRange(contentState, selectionState, 'backward');
        let targetSelection = afterRemoval.getSelectionAfter();
        let afterSplit = Modifier.splitBlock(afterRemoval, targetSelection);
        let insertionTarget = afterSplit.getSelectionAfter();

        let asMedia = Modifier.setBlockType(afterSplit, insertionTarget, `media-${type}`);
        let entityKey = Entity.create('TOKEN', 'IMMUTABLE', {
            src: src
        });

        let charData = CharacterMetadata.create({entity: entityKey});

        let fragmentArray = [
            new ContentBlock({
                key: genKey(),
                type: `media-${type}`,
                text: '',
                characterList: List(Repeat(charData, 1))
            }),
            new ContentBlock({
                key: genKey(),
                type: 'unstyled',
                text: '',
                characterList: List()
            })
        ];
        let fragment = BlockMapBuilder.createFromArray(fragmentArray);
        let withMedia = Modifier.replaceWithFragment(asMedia, insertionTarget, fragment);

        let newContent = withMedia.merge({
            selectionBefore: selectionState,
            selectionAfter: withMedia.getSelectionAfter().set('hasFocus', true)
        });

        this.onChange(EditorState.push(editorState, newContent, 'insert-fragment'), cb);
    }