So, my full apache configuration that solved my problem:
<VirtualHost *:80>
ServerName www.domain.com
Redirect permanent / https://www.domain.com/
</VirtualHost>
<VirtualHost _default_:443>
ServerName www.domain.com
SSLCipherSuite EECDH+AESGCM:EDH+AESGCM:AES256+EECDH:AES256+EDH:ECDHE-RSA-AES128-GCM-SHA384:ECDHE-RSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-GCM-SHA128:DHE-RSA-AES128-GCM-SHA384:DHE-RSA-AES128-GCM-SHA256:DHE-RSA-AES128-GCM-SHA128:ECDHE-RSA-AES128-SHA384:ECDHE-RSA-AES128-SHA128:ECDHE-RSA-AES128-SHA:ECDHE-RSA-AES128-SHA:DHE-RSA-AES128-SHA128:DHE-RSA-AES128-SHA128:DHE-RSA-AES128-SHA:DHE-RSA-AES128-SHA:ECDHE-RSA-DES-CBC3-SHA:EDH-RSA-DES-CBC3-SHA:AES128-GCM-SHA384:AES128-GCM-SHA128:AES128-SHA128:AES128-SHA128:AES128-SHA:AES128-SHA:DES-CBC3-SHA:HIGH:!aNULL:!eNULL:!EXPORT:!DES:!MD5:!PSK:!RC4
SSLProtocol All -SSLv2 -SSLv3
SSLHonorCipherOrder On
SSLEngine on
SSLCertificateFile /etc/apache2/ssl/crt.crt
SSLCertificateKeyFile /etc/apache2/ssl/crt.key
SSLCertificateChainFile /etc/apache2/ssl/crt-ca.crt
ProxyPreserveHost On
ProxyRequests Off
RewriteEngine On
ProxyPass /pentaho ajp://localhost:8009/pentaho/
ProxyPassReverse /pentaho ajp://localhost/8009/pentaho/
RewriteRule /pentaho/(.*)$ ajp://localhost:8009/pentaho/$1 [P]
RewriteRule ^/$ /pentaho [R]
RewriteRule ^/(.*);jsessionid= https://%{HTTP_HOST}$1/ [R=301,L]
RewriteCond %{REQUEST_URI} ^/(pentaho)$
RewriteRule ^(.*)$ https://%{HTTP_HOST}$1/ [R=301,L]
</Virtualhost>
It might not look pretty, but it does the job. Hope it helps someone.