- install Java 8 [here](https://www.oracle.com/technetwork/java/javase/downloads/index.html) and NodeJs [here](https://nodejs.org/en/download/)
- install maven [here](https://maven.apache.org/install.html)
- in folder `backend` run spring boot with following command `mvn spring-boot:run`
[INFO] Scanning for projects...
[INFO]
[INFO] -----------------------< com.akveo:bundle-java >------------------------
[INFO] Building bundle-java 1.0.0
[INFO] --------------------------------[ jar ]---------------------------------
[INFO]
[INFO] >>> spring-boot-maven-plugin:2.1.4.RELEASE:run (default-cli) > test-compile @ bundle-java >>>
[INFO]
[INFO] --- maven-checkstyle-plugin:3.0.0:check (default) @ bundle-java ---
[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 1.370 s
[INFO] Finished at: 2020-05-20T13:11:18+02:00
[INFO] ------------------------------------------------------------------------
[ERROR] Failed to execute goal org.apache.maven.plugins:maven-checkstyle-plugin:3.0.0:check (default) on project bundle-java: Failed during checkstyle execution: Failed during checkstyle configuration: unable to parse configuration stream: sun.security.validator.ValidatorException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target -> [Help 1]
[ERROR]
[ERROR] To see the full stack trace of the errors, re-run Maven with the -e switch.
[ERROR] Re-run Maven using the -X switch to enable full debug logging.
[ERROR]
[ERROR] For more information about the errors and possible solutions, please read the following articles:
[ERROR] [Help 1] http://cwiki.apache.org/confluence/display/MAVEN/MojoExecutionException
Step 3 from instruction fails: