Source code missing

Got it, you’re wanting to bake the sidebar into your plugin? Here’s how that’s done:

/**
 * External Dependencies
 */

/**
 * WordPress Dependencies
 */
import { __ } from '@wordpress/i18n';
import { PluginSidebar, PluginSidebarMoreMenuItem } from '@wordpress/editor';

/**
* Internal Dependencies
*/
import WelcomeGuide from '../../components/welcome-guide';
import pluginIcons from '../../utils/icons';
import Settings from '../../components/settings';
import './index.scss';
const slug = 'draft';

const Plugin = ( props ) => {
	if ( !! wp.data.select('core/editor').getCurrentPostType() ) {
		return (
			<>
				<PluginSidebarMoreMenuItem target={ settings }>
					{ __( 'Draft settings', 'draft' ) }
				</PluginSidebarMoreMenuItem>
				<WelcomeGuide />
				<PluginSidebar
					title={ __(  Draft settings, 'draft' ) }
					name={ settings }
					isPinnable={ false }
				>
					<Settings />
				</PluginSidebar>
			</>
		);
	}
	return (
		<>
			<PluginSidebarMoreMenuItem target={ settings }>
				{ __( 'Draft settings', 'draft' ) }
			</PluginSidebarMoreMenuItem>
			<PluginSidebar
				title={ __(  Draft settings, 'draft' ) }
				name={ settings }
				isPinnable={ false }
			>
				<Settings />
			</PluginSidebar>
		</>
	);
};

const name = ${ slug };
const settings = {
	icon: pluginIcons.plugin,
	render: Plugin,
};

export { name, settings };

I think the key part of the plugin guidelines is this:
We strongly recommend you document how any development tools are to be used.

Otherwise, the source code isn’t obscured in anyway, it’s compiled for production.

Sorry @nico23 I’m not fully understanding the code you wanted and you mentioned being interested in including the entire Gutenberg sidebar. Here’s the code for the class selector:

/**
 * External Dependencies
 */

/**
 * WordPress Dependencies
 */
import { __ } from '@wordpress/i18n';
import { createHigherOrderComponent } from '@wordpress/compose';
import { BlockControls,  InspectorAdvancedControls } from '@wordpress/block-editor';
import { BaseControl, Button, MenuGroup, ToolbarDropdownMenu, TextControl } from "@wordpress/components";
import { dispatch, useSelect } from '@wordpress/data';
import { getPath } from '@wordpress/url';
const { openGeneralSidebar } = dispatch( 'core/edit-post' ) || {};
const { openGeneralSidebar: openGeneralSidebarSiteEditor } = dispatch( 'core/edit-site' ) || {};

/**
 * Internal Dependencies
 */
import ClassPicker from '../../components/class-picker';
import pluginIcons from '../../utils/icons';
import './index.scss';
const slug = 'draft';

const addUtilityClassesToBlockEdit = createHigherOrderComponent(
	( BlockEdit ) => {
		return ( props ) => {
			const {
				setAttributes,
				isSelected,
			} = props;

			let {
				attributes: {
					className,
				},
			} = props;

			const isSiteEditor = getPath( window.location.href )?.includes(
				'site-editor.php'
			);

			const { pluginSettings, isSavingPost, isAutosavingPost } = useSelect(
				( select ) => {

					const pluginSettings = select(
						${ slug }/settings
					).getPluginSettings();

					// const isSavingPost = select('core/editor').isSavingPost();
					// const isAutosavingPost = select('core/editor').isAutosavingPost();

					return {
						pluginSettings,
						// isAutosavingPost,
						// isSavingPost,
					};
			} );

			const { mode } = pluginSettings;

			const onChange = ( newValues, { action, removedValue } ) => {
				if( !! newValues ) {
					className = newValues
						.map( ( newValue ) => {
							let { value } = newValue;

							return value;
						} )
						.toString()
						.replace( /,/g, ' ' );
				}

				if( ! newValues ) {
					className = '';
				}

				setAttributes( {
					className,
				} );
			};

			if( !! className ) {
				className = className.split( ' ' );
				className = className.map( ( option ) => {

					return {
						label: option.replace( 'tw-', '' ),
						value: option,
					};
				} )
			}

			return (
				<>
					<BlockEdit
						{ ...props }
					/>
					{
						mode === 'development' &&
						<>
						<BlockControls
							group="other"
						>
							<ToolbarDropdownMenu
								icon={ pluginIcons.plugin }
								label={ __( 'Add Utility Classes', 'draft' ) }
								popoverProps={ {
									position: 'bottom right',
									variant: 'alternate',
								} }
								menuProps={ { 'className': 'no-icons' } }>
								{ ( { onClose } ) => (
									<>
										<MenuGroup
											className="pb-0"
										>
											<BaseControl
												className="mt-0"
												help={ __( Separate multiple classes with spaces., 'draft' ) }
											>
												<TextControl
													label="Additional CSS Class(es)"
													value={ !! className ? className.map( className => className.value ).toString().replace(/,/g,' ') : '' }
													onChange={ ( nextValue ) => {
														setAttributes( {
															className:
																nextValue !== ''
																	? nextValue
																	: undefined,
														} )
													}	}
												/>
											</BaseControl>
											<ClassPicker
												onChange={ onChange }
												className={ className }
												autofocus={ false }
												blurInputOnSelect={ false }
											/>
										</MenuGroup>
										<MenuGroup>
											<Button variant="link" onClick={ () => isSiteEditor ? openGeneralSidebarSiteEditor( ${ slug }/settings ) : openGeneralSidebar( ${ slug }/settings ) }>{ __( 'Edit default settings', 'draft' ) }</Button>
										</MenuGroup>
									</>
								) }
							</ToolbarDropdownMenu>
						</BlockControls>
						<InspectorAdvancedControls>
							<ClassPicker
								onChange={ onChange }
								className={ className }
								autofocus={ false }
								blurInputOnSelect={ false }
							/>
							<Button variant="link" onClick={ () => isSiteEditor ? openGeneralSidebarSiteEditor( ${ slug }/settings ) : openGeneralSidebar( ${ slug }/settings ) }>{ __( 'Edit default settings', 'draft' ) }</Button>
						</InspectorAdvancedControls>
						</>
					}
				</>
			);
		}
	},
	'addUtilityClassesToBlockEdit'
);

const name = 'add-utility-classes-to-blocks';
const filters = [
	{
		hookName: 'editor.BlockEdit',
		namespace: ${ slug }/add-draft-classes-to-block-edit,
		callback: addUtilityClassesToBlockEdit,
	},
];

export { name, filters };

I think the key part you’re looking for is using the InspectorAdvancedControls component:

import { BlockControls,  InspectorAdvancedControls } from '@wordpress/block-editor';

And then you just drop children in there:

<InspectorAdvancedControls>
							<ClassPicker
								onChange={ onChange }
								className={ className }
								autofocus={ false }
								blurInputOnSelect={ false }
							/>
							<Button variant="link" onClick={ () => isSiteEditor ? openGeneralSidebarSiteEditor( ${ slug }/settings ) : openGeneralSidebar( ${ slug }/settings ) }>{ __( 'Edit default settings', 'draft' ) }</Button>
						</InspectorAdvancedControls>

I’m sharing code snippets to try and help you find what you’re looking for. It’s not resistance so much as the plugin is free, there aren’t many new users using the plugin, few free plugin customers convert to paid plugin customers, and I’m a one person operation. 🥴

Hopefully this gives you the information you need.