Adding linter

.github/workflows/ci-build.yml

@@ -1,4 +1,8 @@
 name: CI Build
+
+env:
+  CIBUILD: true
+
 on:
   workflow_dispatch:
   pull_request:

README.md

@@ -1,5 +1,17 @@
 # ids.server: Server part of ICAT Data Server (IDS)
 
+## Linting
+The [spotless-maven-plugin](https://mvnrepository.com/artifact/com.diffplug.spotless/spotless-maven-plugin) is used here for linting. It uses the Eclipse code formatting feature. The guidelines are defined in `eclipse-formatter.xml` which was initially exported from eclipse (so you can do it again: define rules in eclipse an export the file to use it here).
+
+An automatically code formatting is triggered while local build. In CI builds the code is only validated.
+You also can execute the commands manually:
+* `mvn spotless:check` for validation
+* `mvn spotless:apply` to update the source code like it is defined in the formatters configuration.
+
+### Import order
+The import order is also validated and applied by the spotless-maven-plugin. It is defined in the file `eclipse-importorder.txt` and referenced in `pom.xml`. It is needed that it has a compatible format like the eclipse built-in import order configuration (better its exported file).
+
+## Further Information
 [![Build Status](https://github.com/icatproject/ids.server/workflows/CI%20Build/badge.svg?branch=master)](https://github.com/icatproject/ids.server/actions?query=workflow%3A%22CI+Build%22)
 
 General installation instructions are at http://www.icatproject.org/installation/component