java: refer java1.8 as java8 in download_java.com

This commit uses a fixed JDK version for every JAVA build which is
independent of the value of `VTK_JAVA_VERSION`, this possible since a
newer JDK can produce an older JAVA bytecode using the -release flag
(that we use).

Now `VTK_JAVA_VERSION`only decides the JAVA version of the produced JAVA
bytecode.

.gitlab/ci/download_java.cmake

@@ -9,37 +9,17 @@
 ##============================================================================
 
 cmake_minimum_required(VERSION 3.18 FATAL_ERROR)
-set(java_version 1.8)
-if (DEFINED ENV{VTK_JAVA_VERSION})
-  set(java_version $ENV{VTK_JAVA_VERSION})
-endif()
 
 if ("$ENV{CMAKE_CONFIGURATION}" MATCHES "windows")
-  if(java_version VERSION_EQUAL 1.8)
-    set(jdk_sha256_sum d37df800a005b91bed511e214821abf21ffe78d2c4d84f545268b1bd677e7401)
-    set(jdk_url https://github.com/adoptium/temurin8-binaries/releases/download/jdk8u412-b08/OpenJDK8U-jdk_x64_windows_hotspot_8u412b08.zip)
-    set(jdk_root_dir jdk8u412-b08)
-  elseif(java_version VERSION_EQUAL 11)
-    set(jdk_sha256_sum 69f1c21a176f076bb01e985cf40a18b5772793004bbc4e92983e1ac55bd717e8)
-    set(jdk_url https://download.java.net/openjdk/jdk11.0.0.2/ri/openjdk-11.0.0.2_windows-x64.zip)
-    set(jdk_root_dir jdk-11.0.0.2)
-  else()
-    message(FATAL_ERROR "Unknown platform")
-  endif()
+  set(jdk_sha256_sum 69f1c21a176f076bb01e985cf40a18b5772793004bbc4e92983e1ac55bd717e8)
+  set(jdk_url https://download.java.net/openjdk/jdk11.0.0.2/ri/openjdk-11.0.0.2_windows-x64.zip)
+  set(jdk_root_dir jdk-11.0.0.2)
   set(jdk_ext zip)
 elseif ("$ENV{CMAKE_CONFIGURATION}" MATCHES "macos")
   if ("$ENV{CMAKE_CONFIGURATION}" MATCHES "x86_64")
-    if(java_version VERSION_EQUAL 1.8)
-      set(jdk_sha256_sum fd62491f7634c1cbed7557d6b21db7ef4818fbc0e63e678110d9d92cbea4ad8c)
-      set(jdk_url https://github.com/adoptium/temurin8-binaries/releases/download/jdk8u412-b08/OpenJDK8U-jdk_x64_mac_hotspot_8u412b08.tar.gz)
-      set(jdk_root_dir jdk8u412-b08)
-    elseif(java_version VERSION_EQUAL 11)
-      set(jdk_sha256_sum f365750d4be6111be8a62feda24e265d97536712bc51783162982b8ad96a70ee)
-      set(jdk_url https://download.java.net/java/GA/jdk11/9/GPL/openjdk-11.0.2_osx-x64_bin.tar.gz)
-      set(jdk_root_dir jdk-11.0.2.jdk)
-    else()
-      message(FATAL_ERROR "Unknown platform")
-    endif()
+    set(jdk_sha256_sum f365750d4be6111be8a62feda24e265d97536712bc51783162982b8ad96a70ee)
+    set(jdk_url https://download.java.net/java/GA/jdk11/9/GPL/openjdk-11.0.2_osx-x64_bin.tar.gz)
+    set(jdk_root_dir jdk-11.0.2.jdk)
   elseif ("$ENV{CMAKE_CONFIGURATION}" MATCHES "arm64")
     set(jdk_sha256_sum ac3ff5a57b9d00606e9b319bde7309a4ecb9f2c4ddc0f48d001f234e93b9da86)
     set(jdk_url https://download.oracle.com/java/17/archive/jdk-17.0.11_macos-aarch64_bin.tar.gz)