fix kube-apiserver panic when CRD Kind contains only one letter

Signed-off-by: SataQiu <1527062125@qq.com>

Kubernetes-commit: 2c8c9d02098a975ee3f42c6a6d29579da8502b6d

pkg/endpoints/installer.go

@@ -1070,7 +1070,7 @@ func splitSubresource(path string) (string, string, error) {
 
 // GetArticleForNoun returns the article needed for the given noun.
 func GetArticleForNoun(noun string, padding string) string {
-	if noun[len(noun)-2:] != "ss" && noun[len(noun)-1:] == "s" {
+	if !strings.HasSuffix(noun, "ss") && strings.HasSuffix(noun, "s") {
 		// Plurals don't have an article.
 		// Don't catch words like class
 		return fmt.Sprintf("%v", padding)

pkg/endpoints/installer_test.go

@@ -80,6 +80,16 @@ func TestGetArticleForNoun(t *testing.T) {
 			padding: " ",
 			want:    " a ",
 		},
+		{
+			noun:    "S",
+			padding: " ",
+			want:    " a ",
+		},
+		{
+			noun:    "O",
+			padding: " ",
+			want:    " an ",
+		},
 	}
 	for _, tt := range tests {
 		if got := GetArticleForNoun(tt.noun, tt.padding); got != tt.want {