Summary

Setup:enrich_config (lua/java-dap/setup.lua:41) asserts that
mainClass is present, but attach configs don't have one and don't
need one — the JVM is already running and chose its own main class,
classpath, and java executable.

The assert fires before any check on request type, so every Java
DAP attach config fails today unless callers pre-populate dummy
values for the five fields the early-return checks (mainClass,
projectName, modulePaths, classPaths, javaExec).

This PR adds an early return for config.request == 'attach',
skipping the launch-specific enrichment (build_workspace,
resolve_classpath, resolve_java_executable) which are all
meaningless for an already-running JVM.

Reproduction

Register a Java attach config in dap.configurations.java:

table.insert(dap.configurations.java, {
  type = 'java',
  request = 'attach',
  name = 'Java Attach :5005',
  hostName = '127.0.0.1',
  port = 5005,
})

Start a JDWP-listening JVM (e.g. mvn spring-boot:run -Dspring-boot.run.jvmArguments='-agentlib:jdwp=transport=dt_socket,server=y,suspend=y,address=*:5005'), then :DapContinue and pick that config.

Before this PR:

To enrich the config, mainClass should already be present
.../nvim-java/lua/java-dap/setup.lua:54

After this PR: the attach proceeds, the DAP session initialises,
and breakpoints work as expected.

Why the early-return location

The existing five-field early-return (lines 45-47) lets callers
satisfy the assert by passing dummy values. That works as a
workaround but is unintuitive — attach configs shouldn't have to
fake fields they semantically don't have. Adding the
request == 'attach' short-circuit ahead of it expresses the actual
invariant: attach configs need no enrichment, full stop.

Test plan

• Local install patched with the same change; :DapContinue →
  pick attach config → DAP session attaches, dap-ui opens, breakpoints
  fire on the running JVM.
• Verified request == 'launch' configs still go through the
  full enrichment path (no regression — the early return only fires on
  'attach').

🤖 Generated with Claude Code