From 3dd5069f5a5e5f6244bee4132711f2d59fcbc4cc Mon Sep 17 00:00:00 2001
From: rob bygrave <robin.bygrave@gmail.com>
Date: Thu, 16 May 2019 20:26:45 +1200
Subject: [PATCH] #1698 FIX for IAE "key can't be empty" in
 System.getProperty()

That is, assertEquals("${}", PropertyEval.eval("${}"));
... for when we load properties that include the "${}" placeholder
---
 src/main/java/io/ebean/config/properties/PropertyEval.java   | 3 +++
 .../java/io/ebean/config/properties/PropertyEvalTest.java    | 5 +++++
 2 files changed, 8 insertions(+)

diff --git a/src/main/java/io/ebean/config/properties/PropertyEval.java b/src/main/java/io/ebean/config/properties/PropertyEval.java
index f1763cb3e..753481d7d 100644
--- a/src/main/java/io/ebean/config/properties/PropertyEval.java
+++ b/src/main/java/io/ebean/config/properties/PropertyEval.java
@@ -59,6 +59,9 @@ final class PropertyEval {
 	 */
 	private static String evaluateExpression(String exp) {
 
+    if (exp.isEmpty()) {
+      return null;
+    }
 		if (isJndiExpression(exp)) {
 			// JNDI property lookup...
 			String val = getJndiProperty(exp);
diff --git a/src/test/java/io/ebean/config/properties/PropertyEvalTest.java b/src/test/java/io/ebean/config/properties/PropertyEvalTest.java
index f074ff7a4..ac996943b 100644
--- a/src/test/java/io/ebean/config/properties/PropertyEvalTest.java
+++ b/src/test/java/io/ebean/config/properties/PropertyEvalTest.java
@@ -33,6 +33,11 @@ public class PropertyEvalTest {
 		System.clearProperty("foo");
 	}
 
+  @Test
+  public void eval_emptyPlaceholder() {
+    assertEquals("${}", PropertyEval.eval("${}"));
+  }
+
 	@Test
 	public void eval_singleExpression_withDefault() {