fix: Allowing servers dropdown to change when oas3Actions.setSelectedServer is called (#6358)

ref: #6351

src/core/plugins/oas3/components/servers.jsx

@@ -109,7 +109,8 @@ export default class Servers extends React.Component {
               ( server ) =>
               <option
                 value={ server.get("url") }
-                key={ server.get("url") }>
+                key={ server.get("url") }
+                selected={ currentServer === server.get("url") }>
                 { server.get("url") }
                 { server.get("description") && ` - ${server.get("description")}` }
               </option>

test/e2e-cypress/static/documents/bugs/6351.yaml

@@ -0,0 +1,13 @@
+openapi: 3.0.2
+info:
+  title: OAS 3.0 sample with multiple servers
+  version: 0.1.0
+servers:
+  - url: http://testserver1.com
+  - url: http://testserver2.com
+paths:
+  /test/:
+    get:
+      responses:
+        '200':
+          description: Successful Response

test/e2e-cypress/tests/bugs/6351.js

@@ -0,0 +1,13 @@
+// http://github.com/swagger-api/swagger-ui/issues/6351
+
+describe("#6351: Server dropdown should change when switched via oas3Actions.setSelectedServer", () => {
+  it("should show different selected server", () => {
+    cy.visit("/?url=/documents/bugs/6351.yaml")
+      .get("select")
+      .contains("http://testserver1.com")
+      .window()
+      .then(win => win.ui.oas3Actions.setSelectedServer("http://testserver2.com"))
+      .get("select")
+      .contains("http://testserver2.com")
+  })
+})