Cannot add trusted certificate with assembly layer

[tdiesler]

Describe the bug

I have a plugin configuration like this ...

            <plugin>
                <groupId>org.eclipse.jkube</groupId>
                <artifactId>kubernetes-maven-plugin</artifactId>
                <version>1.18.1</version>
                <configuration>
                    <buildStrategy>docker</buildStrategy>
                    <images>
                        <image>
                            <build>
                                <from>eclipse-temurin:17</from>
                                <entryPoint>
                                    <exec>
                                        <arg>__cacert_entrypoint.sh</arg>
                                        <arg>java</arg>
                                        <arg>-jar</arg>
                                        <arg>/maven/${project.artifactId}-${project.version}.jar</arg>
                                    </exec>
                                </entryPoint>
                                <assembly>
                                    <layers>
                                        <layer>
                                            <id>trusted-certs</id>
                                            <fileSets>
                                                <fileSet>
                                                    <directory>src/main/certs</directory>
                                                    <outputDirectory>/tmp</outputDirectory>
                                                    <includes>
                                                        <include>*crt</include>
                                                    </includes>
                                                </fileSet>
                                            </fileSets>
                                        </layer>
                                    </layers>
                                </assembly>
                            </build>
                        </image>
                    </images>
                </configuration>
                <executions>
                    <execution>
                        <goals>
                            <goal>build</goal>
                            <goal>resource</goal>
                            <goal>push</goal>
                        </goals>
                        <phase>package</phase>
                    </execution>
                </executions>
            </plugin>

and get

[INFO] k8s: [examples/platform-http-oauth:1.0.0]: Created docker-build.tar in 86 milliseconds
[INFO] k8s: Step 1/4 : FROM eclipse-temurin:17
[INFO] k8s: 
[INFO] k8s: ---> 1e83e0efd1de
[INFO] k8s: Step 2/4 : COPY /trusted-certs/maven /maven/
[INFO] k8s: 
[ERROR] k8s: Failed to execute the build [Error while trying to build the image: Unable to build image [examples/platform-http-oauth:1.0.0] : "COPY failed: file not found in build context or excluded by .dockerignore: stat trusted-certs/maven: file does not exist" ]

or

[ERROR] k8s: Failed to execute the build [Error while trying to build the image: Cannot create directory '/certificates'.]

when outputDirectory=/certificates

Eclipse JKube version

1.18.1

Component

Kubernetes Maven Plugin

Apache Maven version

other (please specify in additional context)

Gradle version

None

Steps to reproduce

Build an image from eclipse-temurin:17 with an trusted cert that can get picked up by the temurin provided entrypoint __cacert_entrypoint.sh

Expected behavior

cert gets added to the image at the predefined location i.e. /certificates/mycert.crt

Runtime

Kubernetes (vanilla)

Kubernetes API Server version

1.25.3

Environment

macOS

Eclipse JKube Logs

Sample Reproducer Project

No response

Additional context

No response