Cannot read property 'head' of undefined

I've already seen issue posted here, but nothing helps. My organization has repository `ethernal-project\ethernal-core` which depends on public `SpigotMC/BungeeCord`.

[My defintions file (click for full raw definitions file)](https://gist.githubusercontent.com/rgnter/1484f65a1a2396b870886f74c454abfe/raw/bc2ab1c61e2d0f97f05c15bded58100c0ea0f192/definitions.yml):
```yml
version: "2.1"

# Dependencies
dependencies:
- project: SpigotMC/BungeeCord
- project: ethernal-project/ethernal-core
dependencies:
- project: SpigotMC/BungeeCord

# Builds
default:
build-command:
current: echo "build bungee"
build:
- project: ethernal-project/ethernal-core
build-command:
current: echo "build core"
```

And my action file:
```yml
name: Java CI with Gradle
on:
push:
branches: [ "main" ]
pull_request:
branches: [ "main" ]
permissions:
contents: read
jobs:
build:
runs-on: ubuntu-latest
steps:
# Setup JDK
- uses: actions/checkout@v3
- name: Set up JDK 17
uses: actions/setup-java@v3
with:
java-version: '17'
distribution: 'temurin'

# Build Chain
- name: "Run build-chain"
id: build-chain
uses: kiegroup/github-action-build-chain@v2.6.8
with:
definition-file: https://gist.githubusercontent.com/rgnter/1484f65a1a2396b870886f74c454abfe/raw/bc2ab1c61e2d0f97f05c15bded58100c0ea0f192/definitions.yml
# Build
- name: Build with Gradle
uses: gradle/gradle-build-action@67421db6bd0bf253fb4bd25b31ebb98943c375e1
with:
arguments: build
```

[Here's the log (click for full raw log)](https://gist.github.com/rgnter/e2a17ee801915b5c7bb7ac7173180f02):

Start with the workflow YAML and the linked definitions.yml, then reproduce the failure through the github-action-build-chain@v2.6.8 step using the provided dependency chain. Compare the run with the linked log; done means the action resolves the dependency graph without the "head" error and proceeds to the build steps.

Written by the indexing model from the issue text.