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The 8 Stages of Dev Evolution To AI

Apr 2026, 01. by Sergio del Amo Permalink

What stage are you in your AI-assisted coding journey?

The 8 Stages of Dev Evolution To AI

Stage 1: Zero or Near-Zero AI: maybe code completions, sometimes ask Chat questions
Stage 2: Coding agent in IDE, permissions turned on. A narrow coding agent in a sidebar asks your permission to run tools.
Stage 3: Agent in IDE, YOLO mode: Trust goes up. You turn off permissions, agent gets wider.
Stage 4: In IDE, wide agent: Your agent gradually grows to fill the screen. Code is just for diffs.
Stage 5: CLI, single agent. YOLO. Diffs scroll by. You may or may not look at them.
Stage 6: CLI, multi-agent, YOLO. You regularly use 3 to 5 parallel instances. You are very fast.
Stage 7: 10+ agents, hand-managed. You are starting to push the limits of hand-management.
Stage 8: Building your own orchestrator. You are on the frontier, automating your workflow.

StringTemplate

Jan 2026, 09. by Sergio del Amo Permalink

While reading Spring AI in Action, I discovered StringTemplate.

StringTemplate is a Java template engine for generating source code, web pages, emails, or any other formatted text output. StringTemplate is particularly good at code generators, multiple site skins, and internationalization / localization. StringTemplate also powers ANTLR.

I am thinking of adding support for StringTemplate in Micronaut Views.

String template = """
        You are a helpful assistant, answering questions about tabletop games.
        If you don't know anything about the game or don't know the answer,
        say "I don't know".
        
        The game is {game}.
        
        The question is: {question}.""";
String prompt = new ST(template, '{', '}')
        .add("game", question.gameTitle())
        .add("question", question.question())
        .render();

Micronaut NullAway and JSPecify

Nov 2025, 21. by Sergio del Amo

In this blog post, I show you how to configure a Micronaut 4 application to use JSpecify and NullAway to protect you from NPEs (Null Pointer Exceptions).

NullAway:

NullAway is a tool to help eliminate NullPointerExceptions (NPEs) in your Java code. To use NullAway, first add @Nullable annotations in your code wherever a field, method parameter, or return value may be null. Given these annotations, NullAway performs a series of type-based, local checks to ensure that any pointer that gets dereferenced in your code cannot be null.

JSpecify Dependency

Since Micronaut 4.10, Micronaut BOM contains the JSpecify dependency. Thus, you can add the following dependency to your project without specifying the version:

<dependency>
   <groupId>org.jspecify</groupId>
   <artifactId>jspecify</artifactId>
</dependency>

NullAway with Gradle

GitHub Repository with a Gradle Micronaut Application which uses NullAway

To use NullAway in a Gradle Micronaut Application. You need to add the Gradle error prone plugin and such configuration:

plugins {
...
..
.
    id("net.ltgt.errorprone") version "4.3.0"
}
dependencies {
...
..
.
    implementation("org.jspecify:jspecify")
    errorprone("com.uber.nullaway:nullaway:0.12.12")
    errorprone("com.google.errorprone:error_prone_core:2.44.0")
}
tasks.withType<JavaCompile>().configureEach {
    options.errorprone {
        check("NullAway", net.ltgt.gradle.errorprone.CheckSeverity.ERROR)
        option("NullAway:AnnotatedPackages", example.micronaut")
        if (name.lowercase().contains("test")) {
            disable("NullAway")
        }
    }
}
  • check("NullAway", CheckSeverity.ERROR) sets NullAway issues to the error level.
  • option("NullAway:AnnotatedPackages", “example.micronaut”) tells NullAway that source code in packages under the example.micronaut namespace should be checked for null dereferences and proper usage of @Nullable annotations, and that class files in these packages should be assumed to have correct usage of @Nullable.
  • Then, it disables NullAway on test code.

These instructions are described in the NullAway README.md file.

NullAway with Maven

GitHub Repository with a Maven Micronaut Application which uses NullAway


<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
...
..
.
  <properties>
...
..
.
    <error-prone.version>2.29.2</error-prone.version>
    <nullaway.version>0.12.12</nullaway.version>
  </properties>
...
..
.
  <dependencies>
      <dependency>
          <groupId>org.jspecify</groupId>
          <artifactId>jspecify</artifactId>
          <version>1.0.0</version>
      </dependency>
...
..
.
  </dependencies>
  <build>
    <plugins>
...
..
.
      <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-compiler-plugin</artifactId>
        <configuration>
          <compilerArgs>
            <arg>-XDcompilePolicy=simple</arg>
            <arg>--should-stop=ifError=FLOW</arg>
            <arg>-Xplugin:ErrorProne -Xep:NullAway:ERROR -XepOpt:NullAway:AnnotatedPackages=example.micronaut</arg>
            <arg>-Amicronaut.processing.group=mn.maven.jspecify</arg>
            <arg>-Amicronaut.processing.module=mn-maven-jspecify</arg>
          </compilerArgs>
          <annotationProcessorPaths combine.children="append">
            <path>
              <groupId>com.google.errorprone</groupId>
              <artifactId>error_prone_core</artifactId>
              <version>${error-prone.version}</version>
            </path>
            <path>
              <groupId>com.uber.nullaway</groupId>
              <artifactId>nullaway</artifactId>
              <version>${nullaway.version}</version>
            </path>
            <!-- Existing Micronaut processors -->
...
..
.
          </annotationProcessorPaths>
        </configuration>
      </plugin>
    </plugins>
  </build>
</project>

The above example adds two annotation processors. Error Prone and NullAway.

The previous code sample configures NullAway:

  • -XepOpt:NullAway:AnnotatedPackages sets the list of packages that should be considered properly annotated according to the NullAway convention
  • -Xep:NullAway:ERROR sets the NullAway check severity to ERROR, which should cause compilation to fail when NullAway violations are found.

As described in the error prone Maven documentation, I added a .mvn/jvmconfig file with the following content:

--add-exports jdk.compiler/com.sun.tools.javac.api=ALL-UNNAMED
--add-exports jdk.compiler/com.sun.tools.javac.file=ALL-UNNAMED
--add-exports jdk.compiler/com.sun.tools.javac.main=ALL-UNNAMED
--add-exports jdk.compiler/com.sun.tools.javac.model=ALL-UNNAMED
--add-exports jdk.compiler/com.sun.tools.javac.parser=ALL-UNNAMED
--add-exports jdk.compiler/com.sun.tools.javac.processing=ALL-UNNAMED
--add-exports jdk.compiler/com.sun.tools.javac.tree=ALL-UNNAMED
--add-exports jdk.compiler/com.sun.tools.javac.util=ALL-UNNAMED
--add-opens jdk.compiler/com.sun.tools.javac.code=ALL-UNNAMED
--add-opens jdk.compiler/com.sun.tools.javac.comp=ALL-UNNAMED

A failure looks like:

[INFO] ------------------------------------------------------------------------
[ERROR] Failed to execute goal org.apache.maven.plugins:maven-compiler-plugin:3.14.1:compile (default-compile) on project mn-maven-jspecify: Compilation failure
[ERROR] /Users/sdelamo/github/sdelamo/micronaut-maven-nullaway-demo/src/main/java/example/micronaut/GreetingController.java:[21,39] [NullAway] dereferenced expression greetingService.greet() is @Nullable
[ERROR]     (see http://t.uber.com/nullaway )
[ERROR] 
[ERROR] -> [Help 1]
[ERROR]

Micronaut Fundamentals

Oct 2025, 29. by Sergio del Amo Permalink

During this year, I recorded Micronaut Fundamentals, a video course available for free on Oracle MyLearn with an OCI Free Learning Subscription.

It is a 7-hour and 37-minute course covering the following topics:

  • Introduction to Micronaut
  • Micronaut Documentation
  • Creating your first Micronaut application
  • Using Micronaut in popular IDEs
  • Exploring a Micronaut application
  • Micronaut Build Plugins
  • Micronaut Test
  • Micronaut Core Concepts
  • Serialization
  • Application Events
  • Source Code Generation
  • Configuration
  • Dependency Injection
  • HTTP Client
  • HTTP Server
  • Filters
  • Management Endpoints
  • Logging
  • Validation
  • Error formats
  • Error handling
  • OpenAPI
  • Packaging and distribution
  • GraalVM Native Image
  • Graal Development Kit for Micronaut

Announcement in Oracle Blog.

jCasbin

Oct 2025, 23. by Sergio del Amo Permalink

jCasbin is a powerful and efficient open-source access control library for Java projects. It provides support for enforcing authorization based on various access control models.

System Rules

Oct 2025, 21. by Sergio del Amo Permalink

A collection of JUnit rules for testing code that uses java.lang.System.

Add an MCP Server to VS Code

Oct 2025, 03. by Sergio del Amo

To register a MCP Server in VS Code open the command palette with (CMD + Shift + P) and search for "Add MCP"

Select your MCP Server transport (STDIO or HTTP)

If HTTP, enter your MCP Server URL.

Select whether you want to install the MCP Server globally or for the current workspace only.

Enter your MCP Server in the mcp.json configuration file.

The following example shows an MCP Server which uses Streamable HTTP transport.

{
  "servers": {
    "micronautfun": {
      "url": "https://micronaut.fun/mcp",
      "type": "http"
    }
  },
  "inputs": []
}

You should see your MCP listed as installed.

Add an MCP Server to GitHub Copilot in IntelliJ IDEA

Oct 2025, 03. by Sergio del Amo

To register a MCP Server in GitHub Copilot for IntelliJ IDEA, change to Agent model, click the Tools icon and click Add More Tools...

Enter your MCP Server in the mcp.json configuration file. The following example shows an MCP Server packaged as a FAT jar which uses STDIO transport.

{
	"servers": {
	  "diskspace": {
		"type": "stdio",
		"command": "java",
		"args": ["-jar", "/Users/sdelamo/bin/diskspace-0.1-all.jar"]
	  }

	}
}

Add an MCP Server to Claude Code

Oct 2025, 03. by Sergio del Amo Permalink

You can connect Claude Code to tools via MCP. You can use the claude mcp add command to add an MCP server.

claude mcp add --transport http micronautfun https://micronaut.fun/mcp

The previous command adds an entry in the mcpServers of the project:

"mcpServers": {
   "micronautfun": {
     "type": "http",
     "url": "https://micronaut.fun/mcp"
   }
},

These commands modify the vi $HOME/.claude.json configuration file.

You can list your project MCP servers with the claude mcp list command.

Add an MCP Server to Claude Desktop

Oct 2025, 03. by Sergio del Amo

To register a MCP Server in Claude Desktop, click on Settings, click the Developer, and click Edit Config

Enter your MCP Server in the claude_desktop_config.json configuration file. The following example shows an MCP Server packaged as a FAT jar which uses STDIO transport.

{
  "mcpServers": {
    "diskspace": {
      "command": "java",
      "args": ["-jar", "/Users/sdelamo/bin/diskspace-0.1-all.jar"]
    }
  }
}

OSS-Fuzz

Aug 2025, 02. by Sergio del Amo Permalink

OSS-Fuzz aims to make common open source software more secure and stable by combining modern fuzzing techniques with scalable, distributed execution.

Micronaut is using this great initiative by Google.