docs: extract multiversion javadoc post-build step

Move the multiversion post-build Java selection into a dedicated helper so multiversion.sh only wires sphinx-multiversion. The helper is branch-owned, but it still invokes the checkout-local docs/_utils/javadoc.sh, so historical refs keep their own Maven and docs configuration while using Java 8.

Leave API output cleanup in javadoc.sh instead of duplicating it in the multiversion wrapper. Also harden the Javadoc copy step by failing explicitly when the generated API output directory is empty, avoiding a confusing unexpanded glob error.

Author: dkropachev

docs/_utils/javadoc.sh

@@ -21,8 +21,14 @@ if [[ ! -d "$JAVADOC_SOURCE_DIR" ]]; then
     echo "Javadoc output directory was not generated" >&2
     exit 1
 fi
+shopt -s nullglob
+JAVADOC_FILES=("$JAVADOC_SOURCE_DIR"/*)
+if (( ${#JAVADOC_FILES[@]} == 0 )); then
+    echo "Javadoc output directory is empty" >&2
+    exit 1
+fi
 if [[ -d "$OUTPUT_DIR" ]]; then
     rm -r "$OUTPUT_DIR"
 fi
 mkdir -p "$OUTPUT_DIR"
-mv -f "$JAVADOC_SOURCE_DIR"/* "$OUTPUT_DIR"
+mv -f "${JAVADOC_FILES[@]}" "$OUTPUT_DIR"

docs/_utils/multiversion-javadoc.sh

@@ -0,0 +1,29 @@
+#!/bin/bash
+set -euo pipefail
+
+# sphinx-multiversion runs this script from each temporary checkout. This
+# branch-owned wrapper only selects the Java runtime; the actual Javadocs are
+# still generated by the checkout's own docs/_utils/javadoc.sh so historical
+# refs keep their branch-local docs and Maven configuration.
+
+version_name="${SPHINX_MULTIVERSION_NAME:-unknown}"
+
+if [[ "${version_name}" == scylla-* || "${version_name}" == tags/* ]]; then
+    if [[ -z "${JAVA_HOME_8_X64:-}" ]]; then
+        echo "JAVA_HOME_8_X64 is required to build historical docs for ${version_name}" >&2
+        exit 1
+    fi
+
+    export JAVA_HOME="$JAVA_HOME_8_X64"
+    export PATH="$JAVA_HOME/bin:$PATH"
+    echo "Using Java 8 for historical docs version ${version_name}"
+elif [[ -n "${JAVA_HOME_11_X64:-}" ]]; then
+    export JAVA_HOME="$JAVA_HOME_11_X64"
+    export PATH="$JAVA_HOME/bin:$PATH"
+    echo "Using Java 11 for ${version_name}"
+fi
+
+echo "Building Javadocs for ${version_name} with Java:"
+java -version
+
+bash -e ./docs/_utils/javadoc.sh

docs/_utils/multiversion.sh

@@ -1,43 +1,9 @@
 #! /bin/bash
 set -euo pipefail
 
-REPO_ROOT="$(cd "$(dirname "${BASH_SOURCE[0]}")/../.." && pwd)"
-
-# sphinx-multiversion runs post-build commands from each temporary checkout.
-# Keep using that checkout's own docs/_utils/javadoc.sh and Maven config, but
-# select the Java runtime here so older refs build with the JDK they expect.
-POST_BUILD_JAVADOC='
-set -euo pipefail
-
-version_name="${SPHINX_MULTIVERSION_NAME:-unknown}"
-
-if [[ "${version_name}" == scylla-* || "${version_name}" == tags/* ]]; then
-    if [[ -z "${JAVA_HOME_8_X64:-}" ]]; then
-        echo "JAVA_HOME_8_X64 is required to build historical docs for ${version_name}" >&2
-        exit 1
-    fi
-
-    export JAVA_HOME="$JAVA_HOME_8_X64"
-    export PATH="$JAVA_HOME/bin:$PATH"
-    echo "Using Java 8 for historical docs version ${version_name}"
-elif [[ -n "${JAVA_HOME_11_X64:-}" ]]; then
-    export JAVA_HOME="$JAVA_HOME_11_X64"
-    export PATH="$JAVA_HOME/bin:$PATH"
-    echo "Using Java 11 for ${version_name}"
-fi
-
-echo "Building Javadocs for ${version_name} with Java:"
-java -version
-
-output_dir="docs/_build/dirhtml/api"
-if [[ -n "${SPHINX_MULTIVERSION_OUTPUTDIR:-}" ]]; then
-    output_dir="${SPHINX_MULTIVERSION_OUTPUTDIR}/api"
-fi
-rm -rf "$output_dir"
-
-bash -e ./docs/_utils/javadoc.sh
-'
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+REPO_ROOT="$(cd "$SCRIPT_DIR/../.." && pwd)"
 
 cd "$REPO_ROOT" && sphinx-multiversion docs/source docs/_build/dirhtml \
     --pre-build "bash -c \"(find . -mindepth 2 -name README.md -execdir mv '{}' index.md ';'; find . -mindepth 2 -name README.rst -execdir mv '{}' index.rst ';')\"" \
-    --post-build "bash -c '$POST_BUILD_JAVADOC'"
+    --post-build "bash '$SCRIPT_DIR/multiversion-javadoc.sh'"