From efa7ec78837573a5f5e5beed6623a8d1f0972276 Mon Sep 17 00:00:00 2001
From: sylviamoss <moss@hashicorp.com>
Date: Thu, 3 Dec 2020 18:22:32 +0100
Subject: [PATCH] don't override builder/prov/pproc

---
 packer/plugin/discover.go | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/packer/plugin/discover.go b/packer/plugin/discover.go
index fd636a177..823c186b7 100644
--- a/packer/plugin/discover.go
+++ b/packer/plugin/discover.go
@@ -37,9 +37,16 @@ func (c *Config) GetPlugins() (packer.MapOfBuilder, packer.MapOfProvisioner, pac
 // Hence, the priority order is the reverse of the search order - i.e., the
 // CWD has the highest priority.
 func (c *Config) Discover() error {
-	c.builders = packer.MapOfBuilder{}
-	c.postProcessors = packer.MapOfPostProcessor{}
-	c.provisioners = packer.MapOfProvisioner{}
+	if c.builders == nil {
+		c.builders = packer.MapOfBuilder{}
+	}
+	if c.provisioners == nil {
+		c.provisioners = packer.MapOfProvisioner{}
+	}
+	if c.postProcessors == nil {
+		c.postProcessors = packer.MapOfPostProcessor{}
+	}
+
 	// If we are already inside a plugin process we should not need to
 	// discover anything.
 	if os.Getenv(MagicCookieKey) == MagicCookieValue {