fix test: trim spaces in expression

Author: SylvainJuge

instrumentation/jmx-metrics/library/src/main/java/io/opentelemetry/instrumentation/jmx/yaml/MetricStructure.java

@@ -205,15 +205,15 @@ private static String tryParseFunction(String function, String expression, Strin
     if (!expression.startsWith(function)) {
       return null;
     }
-    String expr = expression.substring(function.length());
+    String expr = expression.substring(function.length()).trim();
     if (expr.charAt(0) != '(' || expr.charAt(expr.length() - 1) != ')') {
       throw new IllegalArgumentException(errorMsg);
     }
-    expr = expr.substring(1, expr.length() - 1);
+    expr = expr.substring(1, expr.length() - 1).trim();
     if (expr.isEmpty()) {
       throw new IllegalArgumentException(errorMsg);
     }
-    return expr;
+    return expr.trim();
   }
 
   private MetricAttribute buildStateMetricAttribute(String key, Map<?, ?> stateMap) {

instrumentation/jmx-metrics/library/src/test/java/io/opentelemetry/instrumentation/jmx/yaml/MetricStructureTest.java

@@ -78,11 +78,13 @@ void metricAttribute_beanParam(String target, String value, String expectedValue
       strings = {
         "missing(name)", // non-existing target
         "param()", // missing parameter
+        "param( )", // missing parameter with empty string
         "param(name)a", // something after parenthesis
         "lowercase()", // misng target in modifier
         "lowercase(param(name)", // missing parenthesis for modifier
         "lowercase(missing(name))", // non-existing target within modifier
         "lowercase(param())", // missing parameter in modifier
+        "lowercase(param( ))", // missing parameter in modifier with empty string
         "lowercase(param))", // missing parenthesis within modifier
       })
   void invalidTargetSyntax(String target) {