Create Spring Boot Kotlin Project
github/awesome-copilot
Create Spring Boot Kotlin Project Skeleton. An agent skill from github/awesome-copilot.
A skill your agent uses when annotating nullability in Spring Boot 3 / Spring Framework 6 code, integrating Kotlin, or adding static nullability checks without assuming Spring Framework 7 JSpecify…
Install Null Safety
$ npx skills add rrezartprebreza/spring-boot-skills --skill null-safety -a claude-codeProject install by default; add -g for ~/.claude/skills/.
$ gh skill install rrezartprebreza/spring-boot-skills null-safety --agent claude-codeProject scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).
$ git clone --depth 1 https://github.com/rrezartprebreza/spring-boot-skills.git skills-src && mkdir -p .claude/skills && cp -r skills-src/skills/spring-boot-3/null-safety .claude/skills/null-safety && rm -rf skills-srcUse ~/.claude/skills/ instead of .claude/skills for a personal install. The folder must contain SKILL.md.
Claude Code skills documentation · loads skills from .claude/skills/
Install the "null-safety" agent skill from https://github.com/rrezartprebreza/spring-boot-skills/tree/main/skills/spring-boot-3/null-safety into .claude/skills/null-safety/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "null-safety", then confirm the skill loads.Claude Code copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$skill-installer install https://github.com/rrezartprebreza/spring-boot-skills/tree/main/skills/spring-boot-3/null-safetyType this inside Codex. $skill-installer <name> installs a curated skill from openai/skills. The installer writes to $CODEX_HOME/skills (default ~/.codex/skills). Restart Codex if the skill does not show up.
$ npx skills add rrezartprebreza/spring-boot-skills --skill null-safety -a codexProject install goes to .agents/skills/; add -g for ~/.codex/skills/.
$ gh skill install rrezartprebreza/spring-boot-skills null-safety --agent codexProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/rrezartprebreza/spring-boot-skills.git skills-src && mkdir -p .agents/skills && cp -r skills-src/skills/spring-boot-3/null-safety .agents/skills/null-safety && rm -rf skills-srcUse ~/.agents/skills/ instead of .agents/skills for a personal install.
Codex skills documentation · loads skills from .agents/skills/
Install the "null-safety" agent skill from https://github.com/rrezartprebreza/spring-boot-skills/tree/main/skills/spring-boot-3/null-safety into .agents/skills/null-safety/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "null-safety", then confirm the skill loads.Codex copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ npx skills add rrezartprebreza/spring-boot-skills --skill null-safety -a cursorProject install goes to .agents/skills/; add -g for ~/.cursor/skills/.
$ gh skill install rrezartprebreza/spring-boot-skills null-safety --agent cursorProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/rrezartprebreza/spring-boot-skills.git skills-src && mkdir -p .cursor/skills && cp -r skills-src/skills/spring-boot-3/null-safety .cursor/skills/null-safety && rm -rf skills-srcUse ~/.cursor/skills/ instead of .cursor/skills for a personal install.
Cursor skills documentation · loads skills from .cursor/skills/, .agents/skills/, .claude/skills/, .codex/skills/
Install the "null-safety" agent skill from https://github.com/rrezartprebreza/spring-boot-skills/tree/main/skills/spring-boot-3/null-safety into .cursor/skills/null-safety/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "null-safety", then confirm the skill loads.Cursor copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ gemini skills install https://github.com/rrezartprebreza/spring-boot-skills.git --path skills/spring-boot-3/null-safety--scope user (default) or --scope workspace; --path is the subfolder of the repo that holds the skill; --consent skips the security confirmation prompt.
$ npx skills add rrezartprebreza/spring-boot-skills --skill null-safety -a gemini-cliProject install goes to .agents/skills/; add -g for ~/.gemini/skills/.
$ gh skill install rrezartprebreza/spring-boot-skills null-safety --agent gemini-cliProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/rrezartprebreza/spring-boot-skills.git skills-src && mkdir -p .gemini/skills && cp -r skills-src/skills/spring-boot-3/null-safety .gemini/skills/null-safety && rm -rf skills-srcUse ~/.gemini/skills/ instead of .gemini/skills for a personal install, then run /skills reload.
Gemini CLI skills documentation · loads skills from .gemini/skills/, .agents/skills/
Install the "null-safety" agent skill from https://github.com/rrezartprebreza/spring-boot-skills/tree/main/skills/spring-boot-3/null-safety into .gemini/skills/null-safety/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "null-safety", then confirm the skill loads.Gemini CLI copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ gh skill install rrezartprebreza/spring-boot-skills null-safetyInstalls for Copilot at project scope by default; add --scope user for a personal install. Preview a skill first with gh skill preview. Needs GitHub CLI 2.90.0 or later (public preview).
$ npx skills add rrezartprebreza/spring-boot-skills --skill null-safety -a github-copilotProject install goes to .agents/skills/; add -g for ~/.copilot/skills/.
$ git clone --depth 1 https://github.com/rrezartprebreza/spring-boot-skills.git skills-src && mkdir -p .github/skills && cp -r skills-src/skills/spring-boot-3/null-safety .github/skills/null-safety && rm -rf skills-srcUse ~/.copilot/skills/ instead of .github/skills for a personal install. Commit .github/skills so cloud agent and code review can use it.
GitHub Copilot skills documentation · loads skills from .github/skills/, .claude/skills/, .agents/skills/
Install the "null-safety" agent skill from https://github.com/rrezartprebreza/spring-boot-skills/tree/main/skills/spring-boot-3/null-safety into .github/skills/null-safety/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "null-safety", then confirm the skill loads.GitHub Copilot copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ npx skills add rrezartprebreza/spring-boot-skills --skill null-safety -a opencodeOpenCode documents no install command of its own. Project install goes to .agents/skills/; add -g for ~/.config/opencode/skills/.
$ gh skill install rrezartprebreza/spring-boot-skills null-safety --agent opencodeProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/rrezartprebreza/spring-boot-skills.git skills-src && mkdir -p .opencode/skills && cp -r skills-src/skills/spring-boot-3/null-safety .opencode/skills/null-safety && rm -rf skills-srcUse ~/.config/opencode/skills/ instead of .opencode/skills for a personal install.
OpenCode skills documentation · loads skills from .opencode/skills/, .claude/skills/, .agents/skills/
Install the "null-safety" agent skill from https://github.com/rrezartprebreza/spring-boot-skills/tree/main/skills/spring-boot-3/null-safety into .opencode/skills/null-safety/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "null-safety", then confirm the skill loads.OpenCode copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
Facts
- Skill name
null-safety- GitHub stars
- 301
- Token cost
- ~429 tokens
- SKILL.md length
- 183 words
- Files
- 4
- Skills in repo
- 51
- Repo updated
- First seen
- Licence
- MIT
At a glance
A skill your agent uses when annotating nullability in Spring Boot 3 / Spring Framework 6 code, integrating Kotlin, or adding static nullability checks without assuming Spring Framework 7 JSpecify…
- Annotating nullability in Spring Boot 3 / Spring Framework 6 code
- Runs Java scripts from its folder
- Integrating Kotlin
- Adding static nullability checks without assuming Spring Framework 7 JSpecify defaults
What it does
Null Safety is an agent skill from rrezartprebreza/spring-boot-skills. Use when annotating nullability in Spring Boot 3 / Spring Framework 6 code, integrating Kotlin, or adding static nullability checks without assuming Spring Framework 7 JSpecify defaults.
Its SKILL.md is about 430 tokens, which your agent loads only when the skill is triggered. The skill folder holds 5 other files (for example `agents/openai.yaml`).
It sits in Backend & APIs, covering Backend development and Android development. It works with Spring Boot and Kotlin. The repository describes itself as: Production-grade Claude Code and Codex skills for Spring Boot developers. The licence is MIT.
When your agent uses it
- Annotating nullability in Spring Boot 3 / Spring Framework 6 code
- Integrating Kotlin
- Adding static nullability checks without assuming Spring Framework 7 JSpecify defaults
Example prompts
- “/null-safety”
What it can do on your machine
Read from SKILL.md and the folder at commit f0c06a0. It shows what the files ask for, not the result of running them.
Tool permissions
Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.
From allowed-tools in the SKILL.md frontmatter.
Runs code
Ships script files (Java), which the agent can run.
From the folder's file list and the shell code blocks in SKILL.md.
Network
No URLs in SKILL.md.
From URLs in SKILL.md, links to its own repository left out.
Credentials
Names no API keys, tokens, secrets or passwords.
From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.
Context cost
Null Safety loads about 429 tokens when it runs. Until then it costs about 50 tokens; SKILL.md has 183 words of instructions outside code blocks.
Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.
Safety
Auto-check passed
The automated check found no risky patterns in SKILL.md.
Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.
SKILL.md
The full file from rrezartprebreza/spring-boot-skills at commit f0c06a0, republished under its MIT licence (© rrezartprebreza). 183 words, ~429 tokens.
Download SKILL.mdSave it as
.claude/skills/null-safety/SKILL.md (or your agent's skills folder). This skill also uses 3 other files; get the full folder from GitHub.- name
- null-safety
- description
- Use when annotating nullability in Spring Boot 3 / Spring Framework 6 code, integrating Kotlin, or adding static nullability checks without assuming Spring Framework 7 JSpecify defaults.
Null Safety (Boot 3 / Framework 6)
Use the nullability model supported by the project. Spring Framework 6 commonly uses
org.springframework.lang.Nullable, @NonNull, and package-level @NonNullApi. JSpecify can be
introduced deliberately, but do not assume Framework 7 migration semantics in a Boot 3 module.
@NonNullApi
package com.example.orders;
import org.springframework.lang.NonNullApi;Annotate genuine nullable results and parameters with @Nullable. Keep repository return types
explicit, validate external input at boundaries, and use Kotlin compiler settings that match the
annotations when Java and Kotlin are mixed. If the project standardizes JSpecify independently,
apply it consistently at module boundaries and document the chosen checker.
Gotchas
- Agent assumes Framework 7 JSpecify defaults - Boot 3 projects usually use Spring's legacy annotations.
- Agent uses
@NonNullApiwithout importing the package annotation - package metadata must compile and be checked in. - Agent marks every value
@NonNull- establish a package default and annotate only nullable exceptions. - Agent treats annotations as runtime validation - use Bean Validation or explicit checks for input validation.
- Agent changes a repository's nullable contract without updating callers - preserve
Optional, nullable, and empty collection semantics. - Agent mixes JSpecify and Spring annotations without a migration plan - choose one module boundary policy.
© rrezartprebreza, MIT. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file
Files
SKILL.md and 3 other files in skills/spring-boot-3/null-safety of rrezartprebreza/spring-boot-skills.
- SKILL.md
- agents/openai.yaml
- examples/bad-null-contract.java
- examples/good-package-info.java
Open the folder on GitHubat commit f0c06a0
Compare with similar skills
Null Safety next to the 5 skills that share the most tags, products or categories with it. Stars are the repository's; “used in” counts other GitHub owners with a copy.
| Skill | Stars | Used in | Tokens | Auto-check | Licence | Repo updated |
|---|---|---|---|---|---|---|
| Null Safety this skillrrezartprebreza/spring-boot-skills | 301 | — | ~429 | Automated safety check: Pass | MIT | |
| Create Spring Boot Kotlin Projectgithub/awesome-copilot | 40k | 1 repos | ~1k | Automated safety check: Pass | MIT | |
| Restart Spring Bootjvm-skills/jvm-skills | 139 | — | ~494 | Automated safety check: Pass | Apache-2.0 | |
| Kotlin Springbootgithub/awesome-copilot | 40k | 1 repos | ~1.1k | Automated safety check: Pass | MIT | |
| Java TestingHoangNguyen0403/agent-skills-standard | 572 | — | ~1k | Automated safety check: Pass | MIT | |
| Test Writeraxelixlabs/axelix | 148 | — | ~2.2k | Automated safety check: Pass | LGPL-3.0 |
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Restart Spring Boot
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Kotlin Springboot
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Java Testing
HoangNguyen0403/agent-skills-standard
Testing standards using JUnit 5, AssertJ, Mockito, Cucumber, and Spring Boot integration tests for Java.
Test Writer
axelixlabs/axelix
Writes new tests for Axelix source code (Java, Kotlin, TypeScript, JavaScript) that follow the project's testing standards — public-API contract coverage, test isolation, given/when/then structure…
Test Reviewer
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Reviews test code in GitHub pull requests for isolation, public-API contract coverage, AAA structure, and correct exception assertions.
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Related
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Questions about Null Safety
What does Null Safety do?
A skill your agent uses when annotating nullability in Spring Boot 3 / Spring Framework 6 code, integrating Kotlin, or adding static nullability checks without assuming Spring Framework 7 JSpecify…. Null Safety is an agent skill from rrezartprebreza/spring-boot-skills. Use when annotating nullability in Spring Boot 3 / Spring Framework 6 code, integrating Kotlin, or adding static nullability checks without assuming Spring Framework 7 JSpecify defaults.
When should I use Null Safety?
Null Safety fits situations like: annotating nullability in Spring Boot 3 / Spring Framework 6 code; integrating Kotlin; adding static nullability checks without assuming Spring Framework 7 JSpecify defaults.
How do I install Null Safety in Claude Code?
Run `npx skills add rrezartprebreza/spring-boot-skills --skill null-safety -a claude-code`. Or copy the skill folder (skills/spring-boot-3/null-safety in rrezartprebreza/spring-boot-skills) into .claude/skills/null-safety in your project. Claude Code loads it when a task matches its description.
How do I install Null Safety in Codex?
Run `npx skills add rrezartprebreza/spring-boot-skills --skill null-safety -a codex`. Or copy the skill folder (skills/spring-boot-3/null-safety in rrezartprebreza/spring-boot-skills) into .agents/skills/null-safety in your project. Codex loads it when a task matches its description.
Can I use Null Safety in Cursor, Gemini CLI or GitHub Copilot?
Cursor, Gemini CLI, GitHub Copilot and OpenCode also load SKILL.md folders. With the skills CLI, run `npx skills add rrezartprebreza/spring-boot-skills --skill null-safety -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/null-safety, .gemini/skills/null-safety, .github/skills/null-safety and .opencode/skills/null-safety in your project.
What does Null Safety need to run?
Going by SKILL.md and its folder, Null Safety needs Java for the scripts in its folder.
Does Null Safety access the network?
SKILL.md contains no URLs. Any network use would come from the scripts or tools the agent runs. This is read from the text; nothing was executed.
Is Null Safety safe to install?
Our automated static check of SKILL.md found no risky patterns, such as piping downloads into a shell, reading credential files or hidden Unicode. It is not a guarantee. Review the folder before installing.
What licence does Null Safety use?
Null Safety is published under the MIT licence (the repository's licence). It allows redistribution, so the full SKILL.md is shown on this page.
How many tokens does Null Safety use?
About 429 tokens (SKILL.md is roughly 1.7k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full.
What are the alternatives to Null Safety?
Skills that share tags, products or a category with Null Safety: Create Spring Boot Kotlin Project (github/awesome-copilot, 40k stars), Restart Spring Boot (jvm-skills/jvm-skills, 139 stars), Kotlin Springboot (github/awesome-copilot, 40k stars) and Java Testing (HoangNguyen0403/agent-skills-standard, 572 stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.
Who maintains Null Safety?
rrezartprebreza (a GitHub user) maintains it in rrezartprebreza/spring-boot-skills, which has 301 GitHub stars. The repository holds 51 skills in this directory. The repository was last updated on September 21, 2026.
Source: rrezartprebreza/spring-boot-skills on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.