Require Java 17 or Java 21 for RPM installations and Java 21 for Fedora installations (#544)

* rpm: Require temurin-21-jre to replace deprecated OpenJDK packages (fixes #516)

* Apply conditional Temurin dependency only for Fedora builds

* Fix: Update Java dependency for Fedora to java >= 21

* Fix: Update Java dependency to java >= 17 for non-Fedora systems

* Fix: correct java requirement syntax

* Restore Requires(pre) line as requested by reviewer

* Update rpm/build/SPECS/jenkins.spec

Co-authored-by: Damien Duportal <damien.duportal@gmail.com>

* Update rpm/build/SPECS/jenkins.spec

Co-authored-by: Damien Duportal <damien.duportal@gmail.com>

---------

Co-authored-by: Damien Duportal <damien.duportal@gmail.com>
Co-authored-by: Bruno Verachten <gounthar@gmail.com>

Author: 3 people

rpm/build/SPECS/jenkins.spec

@@ -19,7 +19,12 @@ BuildRoot:	%{_tmppath}/build-%{name}-%{version}
 # So either we make a hard requirement on the OpenJDK or none at all
 # Only workaround would be to use a java virtual package, see https://github.com/keystep/virtual-java-rpm
 # TODO: If re-enable, fix the matcher for Java 17
-# Requires: java >= 1:1.8.0
+# Fedora 42+ removes openjdk-{8,11,17}. Jenkins now uses Eclipse Temurin JDK 21.
+%if 0%{?fedora}
+Requires: java >= 21
+%else
+Requires: java >= 17
+%endif
 Requires: procps
 Requires(pre): /usr/sbin/useradd, /usr/sbin/groupadd
 BuildArch: noarch