jdtls = {
          settings = {
            java = {
              configuration = {
                runtimes = {
                  {
                    name = 'openjdk-17',
                    path = java_paths['17'],
                    default = true,
                  },
                  {
                    name = 'openjdk-21',
                    path = java_paths['21'],
                  },
                },
              },
            },
          },
        },

...
require('mason-lspconfig').setup {
  ensure_installed = {}, -- explicitly set to an empty table (Kickstart populates installs via mason-tool-installer)
  automatic_installation = false,
  handlers = {
    function(server_name)
      local server = servers[server_name] or {}
      -- This handles overriding only values explicitly passed
      -- by the server configuration above. Useful when disabling
      -- certain features of an LSP (for example, turning off formatting for ts_ls)

      if 'jdtls' == server_name then
        require('java').setup {
          spring_boot_tools = { enable = true, version = '1.55.1' },
          jdk = { auto_install = false },
        }
      end

      server.capabilities = vim.tbl_deep_extend('force', {}, capabilities, server.capabilities or {})
      require('lspconfig')[server_name].setup(server)
    end,
  },
}