Fix the bug of always getting the wrong ssl_key_passphrase value

Author: luming0209

lib/logstash/outputs/syslog.rb

@@ -227,7 +227,7 @@ def setup_ssl
     require "openssl"
     ssl_context = OpenSSL::SSL::SSLContext.new
     ssl_context.cert = OpenSSL::X509::Certificate.new(File.read(@ssl_cert))
-    ssl_context.key = OpenSSL::PKey::RSA.new(File.read(@ssl_key),@ssl_key_passphrase)
+    ssl_context.key = OpenSSL::PKey::RSA.new(File.read(@ssl_key),@ssl_key_passphrase.value || '')
     if @ssl_verify
       cert_store = OpenSSL::X509::Store.new
       # Load the system default certificate path to the store