Java SDK: Describe native Java Dags without reference to Python

[jason810496]

Merge order:

1. Java SDK: Describe native Java Dags without reference to Python #73796 — Describe native Java Dags without reference to Python (current one)
2. Java SDK: Generate Dag and task configuration from the serialization schema #73595 — Generate Dag and task configuration from the serialization schema
3. Java SDK: Resolve a task's arguments from the Dag's own wiring #73596 — Resolve a task's arguments from the Dag's own wiring
4. Java SDK: Declare a Dag's task graph with @Builder.Deps #71189 — Declare a Dag's task graph with @Builder.Deps
5. Java SDK: Serialize native Dags to DagSerialization v3 #71190 — Serialize native Dags to DagSerialization v3

This one is based on main and merges on its own. The rest target main too, because GitHub cannot base a pull request on a branch that exists only on a fork, so their diffs are cumulative and each carries a compare link showing only its own layer. #71188 and #73594, which this stack was built on, are merged, as are #69757 and #71057.

Why

A Dag authored entirely in Java has no Python in the picture, but the native-Dag docs still taught its edge verbs as "Java's spelling of Python's >> and <<" and described the feature as "with no Python stub file". That asks the reader to know a language the feature does not involve.

The mixed-language surface keeps its Python references: there the Python Dag file is part of what the reader has to understand.

What

before / after / Flow.of KDoc, the InterfaceExample header comment and the "Native Java Dags" prose now describe the behaviour directly:

loaded.before(cleaned, notified); // cleanup and notify both wait for load
cleaned.after(loaded, transformed); // cleanup waits for load and transform
Flow.of(a, b).before(c, d); // c and d both wait for a and b

Docs and comments only, no behaviour change.

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Was generative AI tooling used to co-author this PR?

• Yes, with help of Claude Code Opus 5 following the guidelines

[jason810496]

Folded into #73595, which now carries this commit as its first layer, so there is one PR to review for the native-Dag surface instead of two. Closing in favour of that one.

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Drafted-by: Claude Code (Opus 5) (no human review before posting)