RFR: 8371133: Clarify the purpose of "src/jdk.compiler/share/classes/com/sun/tools/javac/resources/ct.properties"

[Jan Lahoda]

On Tue, 4 Nov 2025 08:46:50 GMT, Volkan Yazici <vyazici at openjdk.org> wrote:

> Document usage and purpose of `ct.properties`.

src/jdk.compiler/share/classes/com/sun/tools/javac/resources/ct.properties line 26:

> 24: #
> 25: 
> 26: # This file is used by `com.sun.tools.javac.file.JRTIndex` to generate

How about phrasing like this (`JRTIndex` uses the data defined here, but does not generate the `.java` file - parts of the build system do):

# This file was originally used to produce the `proprietary` warning when
# accessing non-APIs, and to hide some non-APIs in JDK <= 8. This has been
# superseded by the module system and `--release`. But, when compiling with
# `--source 8`, it is still used for this purpose by `com.sun.tools.javac.file.JRTIndex`.
#
# The build generates `jdk.compiler/com/sun/tools/javac/resources/ct.java` from
# this file, which is then used at runtime.

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PR Review Comment: https://git.openjdk.org/jdk/pull/28123#discussion_r2489747244