Convert SEVERITY constants to type-safe enum

[Copilot]

Overview

This PR modernizes the severity level API by converting the integer constants SEVERITY_WARNING and SEVERITY_ERROR to a type-safe enum, addressing issue #XX.

Problem

The current implementation uses primitive integer constants for severity levels:

int SEVERITY_WARNING = 1;
int SEVERITY_ERROR = 2;

void addMessage(File file, int line, int column, String message, int severity, Throwable cause);

This approach has several drawbacks:

• No type safety: Any integer value can be passed (e.g., 999, -1, 42)
• Poor readability: Magic numbers like 1 and 2 are less clear than named constants
• Limited IDE support: No autocomplete for valid values
• Harder to maintain: Adding new severity levels requires careful coordination

Solution

Introduced a new Severity enum with WARNING and ERROR values:

public enum Severity {
    WARNING(1),
    ERROR(2);
    
    public int getValue() { ... }
    public static Severity fromValue(int value) { ... }
}

Added a new type-safe method signature:

void addMessage(File file, int line, int column, String message, Severity severity, Throwable cause);

Benefits

• ✅ Type-safe: Compiler enforces only valid severity values
• ✅ Readable: Severity.WARNING is clearer than 1
• ✅ IDE-friendly: Full autocomplete and refactoring support
• ✅ Future-proof: Easy to add new levels (INFO, DEBUG) mentioned in Please output INFO messages in DefaultBuildContext.addMessage #20
• ✅ Backward compatible: Existing code continues to work

Backward Compatibility

All existing code continues to work without modification:

• Old SEVERITY_WARNING and SEVERITY_ERROR constants remain available (deprecated)
• Old addMessage(int severity) method still works (deprecated)
• Automatic conversion between int and enum values via getValue() and fromValue()

Migration Path

Old code (still works):

buildContext.addMessage(file, 1, 1, "message", BuildContext.SEVERITY_WARNING, null);

New code (recommended):

buildContext.addMessage(file, 1, 1, "message", Severity.WARNING, null);

Changes

• New: src/main/java/org/codehaus/plexus/build/Severity.java - Type-safe enum
• Modified: BuildContext.java - Added enum-based method, deprecated int-based API
• Modified: DefaultBuildContext.java - Implements both enum and deprecated int-based methods

Fixes #XX

Original prompt

---

This section details on the original issue you should resolve

<issue_title>Make SEVERITY a enum?</issue_title>
<issue_description>Currently there are

 /** Constant <code>SEVERITY_WARNING=1</code> */
  int SEVERITY_WARNING = 1;

  /** Constant <code>SEVERITY_ERROR=2</code> */
  int SEVERITY_ERROR = 2;

it might be better to have these (together with INFO and probably DEBUG see #20 )as an Enum to make the code more type safe</issue_description>

Comments on the Issue (you are @copilot in this section)

@michael-o Yes, this is quite old style...

Fixes #40

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[laeubi]

@slachiewicz actually I won't do it here, instead we should define a new dedicated marker API (that by default delegates to the "old" Buildcontext. This then could then use all cool stuff and I think a builder pattern would be mor suitable given the large amount of parameters here that are hard to handle.

If you like I can describe it in an issue and ask copilote to work on this :-D

[slachiewicz]

Feel free to propose a solution, I hope You can also ask the Copilot for a solution. I don't want to be a forwarder here :-)
I saw a few old tickets and thought that it may be easy to fix it this way.