spring-boot/config/checkstyle/import-control.xml

<?xml version="1.0"?>
<!DOCTYPE import-control PUBLIC "-//Checkstyle//DTD ImportControl Configuration 1.4//EN" "https://checkstyle.org/dtds/import_control_1_4.dtd">
<import-control pkg="org.springframework.boot">
	<allow pkg="io.micrometer.observation" />
	<disallow pkg="io.micrometer" />
	<allow class="org.springframework.lang.Contract" />
	<disallow pkg="org.springframework.lang" />
	<allow pkg=".*" regex="true" />

	<subpackage name="autoconfigure">
		<disallow class="org.springframework.boot.autoconfigure.jdbc.DataSourceProperties"/>
		<subpackage name="web">
			<allow pkg="org.springframework.boot.web.server" />
			<allow pkg="org.springframework.boot.web.servlet.server" />
			<disallow pkg="org.springframework.boot.web" />
			<disallow pkg="org.springframework.web.servlet" />
			<disallow pkg="org.springframework.web.reactive" />
			<disallow pkg="jakarta.servlet" />
			<subpackage name="client">
				<allow pkg="org.springframework.boot.web.client" />
			</subpackage>
			<subpackage name="server">
				<allow pkg="org.springframework.boot.web.server" />
				<subpackage name="reactive">
					<allow pkg="org.springframework.boot.web.reactive.server" />
				</subpackage>
				<subpackage name="servlet">
					<allow pkg="jakarta.servlet" />
					<allow pkg="org.springframework.boot.web.servlet" />
					<allow pkg="org.springframework.boot.web.error" />
					<allow pkg="org.springframework.web.servlet" />
				</subpackage>
			</subpackage>
			<subpackage name="servlet">
				<allow pkg="jakarta.servlet" />
				<allow pkg="org.springframework.boot.web.servlet" />
				<allow pkg="org.springframework.web.servlet" />
				<subpackage name="error">
					<allow pkg="org.springframework.boot.web.error" />
				</subpackage>
			</subpackage>
			<subpackage name="reactive">
				<allow pkg="org.springframework.boot.web.codec" />
				<allow pkg="org.springframework.boot.web.reactive" />
				<allow pkg="org.springframework.web.reactive" />
				<subpackage name="error">
					<allow pkg="org.springframework.boot.web.error" />
				</subpackage>
			</subpackage>
		</subpackage>
	</subpackage>

	<subpackage name="metrics">
		<allow pkg="io.micrometer" />
	</subpackage>

	<subpackage name=".*\.metrics" regex="true">
		<allow pkg="io.micrometer" />
	</subpackage>

	<subpackage name=".*\.autoconfigure" regex="true">
		<allow pkg="io.micrometer" />
	</subpackage>

	<subpackage name="[^.]+\.actuate" regex="true">
		<subpackage name="endpoint">
			<file name=".*Endpoint(WebExtension)?" regex="true">
				<allow pkg="org.springframework.lang"/>
			</file>
		</subpackage>
	</subpackage>

	<subpackage name="actuate">
		<!-- Endpoint infrastructure -->
		<subpackage name="endpoint">
			<disallow pkg="org.springframework.http" />
			<disallow pkg="org.springframework.web" />
			<subpackage name="invoke">
				<subpackage name="reflect">
					<file name="OperationMethodParameter">
						<allow pkg="org.springframework.lang"/>
					</file>
				</subpackage>
			</subpackage>
			<subpackage name="web">
				<allow pkg="org.springframework.http" />
				<allow pkg="org.springframework.web" />
				<subpackage name="servlet">
					<disallow pkg="org.springframework.web.reactive" />
				</subpackage>
				<subpackage name="reactive">
					<disallow pkg="org.springframework.web.servlet" />
				</subpackage>
			</subpackage>
		</subpackage>
	</subpackage>

	<subpackage name="docs">
		<allow pkg="io.micrometer" />
	</subpackage>

	<!-- Logging -->
	<subpackage name="logging">
		<allow pkg="org.springframework.boot.context.properties" />
		<allow pkg="org.springframework.boot.context.properties.bind" />
		<allow pkg="org.springframework.context.aot" />
		<disallow pkg="org.springframework.context" />
		<disallow pkg="org.springframework.boot.context" />
	</subpackage>

	<subpackage name="test">
		<subpackage name="autoconfigure">
			<subpackage name="actuate">
				<allow pkg="io.micrometer" />
			</subpackage>
		</subpackage>
	</subpackage>

	<!-- Web related concerns -->
	<subpackage name="web">

		<!-- Lock things down -->
		<disallow pkg="org.springframework.boot.web" />
		<disallow pkg="org.springframework.web.servlet" />
		<disallow pkg="jakarta.servlet" />

		<!-- Common -->
		<subpackage name="client">
		</subpackage>
		<subpackage name="context">
			<allow pkg="org.springframework.context" />
			<subpackage name="servlet">
				<allow pkg="org.springframework.boot.web.servlet" />
				<allow pkg="jakarta.servlet" />
			</subpackage>
		</subpackage>
		<subpackage name="server">
			<allow pkg="org.springframework.boot.web.error" />
			<allow pkg="org.springframework.boot.web.server" />
			<disallow pkg="org.springframework.context" />
			<subpackage name="autoconfigure">
				<allow pkg="org.springframework.context" />
				<subpackage name="servlet">
					<allow pkg="jakarta.servlet" />
					<allow pkg="org.springframework.boot.web.servlet" />
				</subpackage>
			</subpackage>
			<subpackage name="context">
				<allow pkg="org.springframework.context" />
			</subpackage>
			<subpackage name="reactive">
				<subpackage name="context">
					<allow pkg="org.springframework.context" />
					<allow pkg="org.springframework.web.context" />
					<allow pkg="org.springframework.boot.web.context.reactive" />
				</subpackage>
			</subpackage>
			<subpackage name="servlet">
				<allow pkg="jakarta.servlet" />
				<allow pkg="org.springframework.boot.web.servlet" />
				<subpackage name="context">
					<allow pkg="org.springframework.context" />
					<allow pkg="org.springframework.web.context" />
					<allow pkg="org.springframework.boot.web.context.servlet" />
				</subpackage>
			</subpackage>
			<subpackage name="test">
				<allow pkg=".*" regex="true" />
			</subpackage>
		</subpackage>

		<!-- Servlet -->
		<subpackage name="servlet">
			<allow pkg="jakarta.servlet" />
			<subpackage name="filter">
				<allow pkg="jakarta.servlet" />
				<allow pkg="org.springframework.boot.web.servlet" />
			</subpackage>
			<subpackage name="support">
				<allow pkg="jakarta.servlet" />
				<allow pkg="org.springframework.boot.web.error" />
				<allow pkg="org.springframework.boot.web.context.servlet" />
				<allow pkg="org.springframework.boot.web.servlet" />
			</subpackage>
			<subpackage name="view">
				<allow pkg="org.springframework.web.servlet" />
			</subpackage>
			<subpackage name="error">
				<allow pkg="org.springframework.boot.web.error" />
				<allow pkg="org.springframework.web.servlet" />
			</subpackage>
		</subpackage>

		<!-- Reactive -->
		<subpackage name="reactive">
			<subpackage name="context">
				<allow pkg="org.springframework.boot.web.context" />
			</subpackage>
			<subpackage name="error">
				<allow pkg="org.springframework.boot.web.error" />
			</subpackage>
			<subpackage name="result">
				<subpackage name="view">
					<allow pkg="org.springframework.boot.web.reactive.result.view" />
				</subpackage>
			</subpackage>
		</subpackage>

	</subpackage>

</import-control>