chore: add example for plantuml

diff --git a/examples/BUILD.bazel b/examples/BUILD.bazel
index 3b912b5..af2b6c5 100644
--- a/examples/BUILD.bazel
+++ b/examples/BUILD.bazel

@@ -1 +1,9 @@
 # exports_files(["doxygen"])
+load("@doxygen//:doxygen.bzl", "doxygen")
+
+doxygen(
+    name = "doxygen",
+    srcs = ["//:README.md"],
+    project_brief = "Root folder example",
+    project_name = "root",
+)

diff --git a/examples/MODULE.bazel b/examples/MODULE.bazel
index 3a4d7a1..0ef1489 100644
--- a/examples/MODULE.bazel
+++ b/examples/MODULE.bazel

@@ -10,6 +10,16 @@
 bazel_dep(name = "aspect_bazel_lib", version = "2.10.0")
 bazel_dep(name = "bazel_skylib", version = "1.7.1")
 bazel_dep(name = "rules_python", version = "1.2.0")
+bazel_dep(name = "platforms", version = "0.0.10")
+bazel_dep(name = "rules_java", version = "8.15.1")
+
+http_file = use_repo_rule("@bazel_tools//tools/build_defs/repo:http.bzl", "http_file")
+http_file(
+    name = "plantuml_file",
+    urls = ["https://github.com/plantuml/plantuml/releases/download/v1.2025.4/plantuml-1.2025.4.jar"],
+    sha256 = "26518e14a3a04100cd76c0d96cab2d1171f36152215edd9790a28d20268200c1",
+    downloaded_file_path = "plantuml.jar",
+)
 
 pip = use_extension("@rules_python//python/extensions:pip.bzl", "pip")
 pip.parse(

diff --git a/examples/plantuml/BUILD.bazel b/examples/plantuml/BUILD.bazel
new file mode 100644
index 0000000..0e5e93e
--- /dev/null
+++ b/examples/plantuml/BUILD.bazel

@@ -0,0 +1,27 @@
+load("@doxygen//:doxygen.bzl", "doxygen")
+load("@aspect_bazel_lib//lib:copy_file.bzl", "copy_file")
+
+# This is highly advised to avoid chasing the jar file who knows where
+# Instead, we copy it in the OUTDIR folder
+copy_file(
+    name = "plantuml",
+    src = "@plantuml_file//file",
+    out = "plantuml.jar",
+    allow_symlink = False,
+    is_executable = False,
+)
+
+doxygen(
+    name = "doxygen",
+    srcs = [
+        "lib.h",
+        ":plantuml",
+    ],
+    plantuml_jar_path = "$(OUTDIR)",
+    project_brief = "Example project for doxygen",
+    project_name = "Plantuml example",
+    tools = [
+        # Using the java executable from `rules_java`
+        "@rules_java//toolchains:current_java_runtime",
+    ],
+)

diff --git a/examples/plantuml/README.md b/examples/plantuml/README.md
new file mode 100644
index 0000000..0589ffa
--- /dev/null
+++ b/examples/plantuml/README.md

@@ -0,0 +1,59 @@
+# Plantuml example
+
+This is an example of how to use the `doxygen` alongside `plantuml` to generate UML diagrams for C++ classes.
+You will need to provide the `plantuml.jar` file to the rule, as well as the `java` executable.
+
+The JAR can be downloaded from the [plantuml releases page](https://github.com/plantuml/plantuml/releases).
+
+```bzl
+# We will use the Java toolchain from rules_java to run the JAR
+bazel_dep(name = "rules_java", version = "8.15.1")
+
+
+http_file = use_repo_rule("@bazel_tools//tools/build_defs/repo:http.bzl", "http_file")
+http_file(
+    name = "plantuml_file",
+    urls = ["https://github.com/plantuml/plantuml/releases/download/v1.2025.4/plantuml-1.2025.4.jar"],
+    sha256 = "26518e14a3a04100cd76c0d96cab2d1171f36152215edd9790a28d20268200c1",
+    downloaded_file_path = "plantuml.jar",
+)
+```
+
+## Using the JAR
+
+Since the location of the JAR can be difficult to determine, we recommend copying it to the `OUTDIR` folder using the `copy_file` rule from `aspect_bazel_lib`.
+
+```bzl
+load("@aspect_bazel_lib//lib:copy_file.bzl", "copy_file")
+
+# This is highly advised to avoid chasing the jar file who knows where
+# Instead, we copy it in the OUTDIR folder
+copy_file(
+    name = "plantuml",
+    src = "@plantuml_file//file",
+    out = "plantuml.jar",
+    allow_symlink = False,
+    is_executable = False,
+)
+```
+
+Lastly, you can use the `doxygen` rule as follows:
+
+```bzl
+load("@doxygen//:doxygen.bzl", "doxygen")
+
+doxygen(
+    name = "doxygen",
+    srcs = [
+        "lib.h",
+        ":plantuml",
+    ],
+    plantuml_jar_path = "$(OUTDIR)",
+    project_brief = "Example project for doxygen",
+    project_name = "Plantuml example",
+    tools = [
+        # Using the java executable from `rules_java`
+        "@rules_java//toolchains:current_java_runtime",
+    ],
+)
+```

diff --git a/examples/plantuml/lib.h b/examples/plantuml/lib.h
new file mode 100644
index 0000000..4dd0ecf
--- /dev/null
+++ b/examples/plantuml/lib.h

@@ -0,0 +1,22 @@
+/**
+ * @file lib.h
+ * @author Ernesto Casablanca (casablancaernesto@gmail.com)
+ * @copyright 2024
+ */
+#pragma once
+
+/**
+ * @brief Add two integers
+ *
+ * Who knows what the result will be?
+ * In the meantime, look at the graph!
+ * @startuml "Insightful diagram" width=5cm
+ * Alice -> Bob : Hello
+ * @enduml
+ * @note This function is very complex. Use it with caution.
+ * @warning The result can be greater than the maximum value that can be stored!
+ * @param a First integer
+ * @param b Second integer
+ * @return Sum of a and b
+ */
+int add(int a, int b);