Ubuntu – How to find out where $MANPATH is set

From my point of view, the best way is to add the following lines at the ~/.zshrc file (if you don't already have it, then create it):

if [ -d "/path/to/jdk" ] ; then
    export PATH="/path/to/jdk/bin:$PATH"
fi

Then restart your zsh, or just run source ~/.zshrc and then your PATH should be exactly as you wish.

Or, if you want to make the change to be system-wide, then add the previous code to the end of /etc/zsh/zshenv file.

But in any case do not use /etc/profile.d to automatically run scripts in zsh. This directory is useful only for the bash shell, not zsh as in your case. To understand this, open /etc/profile file, which is a bash initialization file and in no case a zsh initialization file, and you will see somewhere at the end of the file:

if [ -d /etc/profile.d ]; then
  for i in /etc/profile.d/*.sh; do
    if [ -r $i ]; then
      . $i
    fi
  done
  unset i
fi

So, your scripts from /etc/profile.d directory will automatically run in zsh only if you add the previous code in a zsh initialization file, like /etc/zsh/zprofile for example, or source /etc/profile in /etc/zsh/zprofile file.

The example in the wiki, for setting session variables via ~/.pam_environment, states in a note:

The syntax used for modifying PATH, which syntax differs from script files, is required for variable expansion to work.

Hence your first row should look like:

ANDROID_HOME DEFAULT=${HOME}/Android/Sdk