Add basic Java generot usage instructions

README.md

@@ -33,6 +33,8 @@ This client provides access to the full [Kubernetes](http://kubernetes.io/) &
     - [Passing a reference of a resource to the client](#passing-a-reference-of-a-resource-to-the-client)
     - [Adapting a client](#adapting-the-client)
         - [Adapting and close](#adapting-and-close)
+- [Generating CRD from Java](doc/CRD-generator.md)
+- [Generating Java from CRD](doc/java-generation-from-CRD.md)
 - [Mocking Kubernetes](#mocking-kubernetes)
 - [Who Uses Fabric8 Kubernetes Client?](#who-uses-kubernetes--openshift-java-client)
 - [Kubernetes Operators in Java Written using Fabric8 Kubernetes Client](./doc/KubernetesOperatorsInJavaWrittenUsingFabric8.md)

doc/java-generation-from-CRD.md

@@ -0,0 +1,123 @@
+# Java generation from CRD (preview)
+
+This document shows how to generate java sources from CRD manifests.
+
+## Quick start CLI
+
+The Java generator CLI is available for download on Sonatype at the link:
+
+```
+https://oss.sonatype.org/content/repositories/releases/io/fabric8/java-generator-cli/<version>/java-generator-cli-<version>.sh
+```
+
+you can get it working locally with few lines:
+
+```bash
+export VERSION=$(wget -q -O - http://github.com/fabric8io/kubernetes-client/releases/latest --header "Accept: application/json" | jq -r '.tag_name' | cut -c 2-)
+wget https://oss.sonatype.org/content/repositories/releases/io/fabric8/java-generator-cli/$VERSION/java-generator-cli-$VERSION.sh
+chmod a+x java-generator-cli-$VERSION.sh
+./java-generator-cli-$VERSION.sh --version
+```
+
+Alternatively, if you already have [jbang](https://www.jbang.dev/) installed, you can run the CLI using it:
+
+```bash
+jbang io.fabric8:java-generator-cli:<version>
+```
+
+## Quick start Maven
+
+The Java generator Maven plugin can be used from your project `pom.xml` adding a section like:
+
+```xml
+<plugin>
+  <groupId>io.fabric8</groupId>
+  <artifactId>java-generator-maven-plugin</artifactId>
+  <version>${kubernetes-client.version}</version>
+  <executions>
+    <execution>
+      <goals>
+        <goal>generate</goal>
+      </goals>
+    </execution>
+  </executions>
+  <configuration>
+    <source>src/main/resources/kubernetes</source>
+    ...
+  </configuration>
+</plugin>
+```
+
+## Usage
+
+Provide a `source` referencing a file or a folder containing your CRDs definitions in `yaml` or `json` format and a `target` directory where the relevant Java code should be generated.
+
+The full list of options of the CLI is (output of `--help`):
+
+```
+Usage: java-gen [-hV] [-add-extra-annotations] [-enum-uppercase] -s=<source>
+                [-suffix-strategy=<suffixStrategy>] -t=<target>
+      -add-extra-annotations, --add-extra-annotations
+                          Add extra lombok and sundrio annotation to the
+                            generated classes
+      -enum-uppercase, --enum-uppercase
+                          Uppercase the enum values
+  -h, --help              Show this help message and exit.
+  -s, --source=<source>   The source(file or folder) with the
+                            CustomResourceDefinition(s) to use
+      -suffix-strategy, --suffix-strategy=<suffixStrategy>
+                          The suffix strategy to be used
+  -t, --target=<target>   The folder to write the generated sources
+  -V, --version           Print version information and exit.
+```
+
+And the corresponding configurations of the Maven plugin are (output of `mvn help:describe -DgroupId=io.fabric8 -DartifactId=java-generator-maven-plugin -Dversion=<version> -Ddetail`):
+
+```
+    enumUppercase
+      User property: fabric8.java-generator.enum-uppercase
+
+    extraAnnotations
+      User property: fabric8.java-generator.extra-annotations
+
+    source
+      Required: true
+      User property: fabric8.java-generator.source
+
+    suffixStrategy
+      User property: fabric8.java-generator.suffix-strategy
+
+    target (Default: ${basedir}/target/generated-sources/java)
+      User property: fabric8.java-generator.target
+```
+
+## Compiling the generated code
+
+The generated code depends on a few dependencies to succesfully compile:
+
+```xml
+<dependency>
+  <groupId>io.fabric8</groupId>
+  <artifactId>kubernetes-client</artifactId>
+</dependency>
+<dependency>
+  <groupId>javax.validation</groupId>
+  <artifactId>validation-api</artifactId>
+  <version>2.0.1.Final</version>
+  <scope>provided</scope>
+</dependency>
+```
+
+and, if `--add-extra-annotations`/`extraAnnotations` has been set, the following dependencies should be included as well:
+```xml
+<dependency> 
+  <groupId>io.sundr</groupId> 
+  <artifactId>builder-annotations</artifactId> 
+  <scope>provided</scope> 
+</dependency> 
+<dependency> 
+  <groupId>org.projectlombok</groupId> 
+  <artifactId>lombok</artifactId> 
+  <scope>provided</scope> 
+</dependency>
+```