feat: Add builder interface for plugins to provide DSL to construct i…

…nteractions

consumer/src/main/kotlin/au/com/dius/pact/consumer/dsl/PactBuilder.kt

@@ -47,6 +47,16 @@ interface DslBuilder {
   fun addPluginConfiguration(matcher: ContentMatcher, pactConfiguration: Map<String, JsonValue>)
 }
 
+/**
+ * Sets up the data required by a plugin to configure an interaction
+ */
+interface PluginInteractionBuilder {
+  /**
+   * Construct the map of configuration that is to be passed through to the plugin
+   */
+  fun build(): Map<String, Any?>
+}
+
 /**
  * Pact builder DSL that supports V4 formatted Pact files
  */
@@ -297,6 +307,16 @@ open class PactBuilder(
     return this
   }
 
+  /**
+   * Configure the interaction using a builder supplied by the plugin author.
+   */
+  fun with(builder: PluginInteractionBuilder): PactBuilder {
+    require(currentInteraction != null) {
+      "'with' must be preceded by 'expectsToReceive'"
+    }
+    return with(builder.build())
+  }
+
   override fun addPluginConfiguration(matcher: ContentMatcher, pactConfiguration: Map<String, JsonValue>) {
     if (pluginConfiguration.containsKey(matcher.pluginName)) {
       pluginConfiguration[matcher.pluginName].deepMerge(pactConfiguration)