This PR is intentionally opened as a draft to gather feedback on the overall approach.

Related Issue

Closes #45306

Goal

Add support for passing Buildpacks environment variables to the bootBuildImage task via CLI options.

This is particularly useful for CI pipelines and automated local workflows (e.g., Kubernetes, Skaffold, or Tilt), where modifying build.gradle or pom.xml to set dynamic values is often undesirable.

Background

In BootBuildImage, the environment configuration is currently defined as a MapProperty<String, String>:

@Input
public abstract MapProperty<String, String> getEnvironment();

However, Gradle’s "Option" annotation does not support Map types, making it impossible to directly expose this property as a CLI option.

As discussed in #45306, this PR explores an alternative approach where CLI-provided values are collected separately as a list and then mapped into the existing environment property.

Approach

1. Introduce a CLI-only input:
   Use an "Internal" ListProperty to capture the raw options provided by the user.

2. Validation & Parsing:
   The input strings are parsed into key-value pairs at execution time.

• Strictly enforces the KEY=VALUE format.

• If the format is invalid (e.g., missing the = separator), the task fails immediately with a GradleException to provide clear feedback to the user.

• Example error: "Invalid value for option '--environment'. Expected 'NAME=VALUE' but got '...'."

3. Merge:
   The parsed values are merged into the existing environment (MapProperty), allowing CLI options to complement or override build script configurations.

CLI Usage

./gradlew bootBuildImage \
  --environment BP_LIVE_RELOAD_ENABLED=true \
  --environment BPL_JAVA_NMT_ENABLED=false

• The --environment option is repeatable
• Each entry must be provided in KEY=VALUE format