The migration was very fast using a perl script to rename the packages:
#!/bin/bash
find . -type f \( -iname \*.scala -o -iname \*.sbt \) -exec perl -pi -e '
undef $/;
use Regexp::Common;
$x= "(){"."}";
$bp = "(?:$RE{balanced}{-parens=>$x})";
$arg = "(?:[^()}{,]*$bp?)+";
s/elasticsearch/opensearch/g;
' {} +
chcase -rd -x 's/elasticsearch/opensearch/g' .