Share SpelExpressionParser in SpelValueExpressionResolver

See gh-46532

Signed-off-by: Johnny Lim <[email protected]>

Author: izeye

module/spring-boot-observation/src/main/java/org/springframework/boot/observation/autoconfigure/SpelValueExpressionResolver.java

@@ -30,12 +30,13 @@
  */
 class SpelValueExpressionResolver implements ValueExpressionResolver {
 
+	private final ExpressionParser expressionParser = new SpelExpressionParser();
+
 	@Override
 	public String resolve(String expression, Object parameter) {
 		try {
 			SimpleEvaluationContext context = SimpleEvaluationContext.forReadOnlyDataBinding().build();
-			ExpressionParser expressionParser = new SpelExpressionParser();
-			Expression expressionToEvaluate = expressionParser.parseExpression(expression);
+			Expression expressionToEvaluate = this.expressionParser.parseExpression(expression);
 			return expressionToEvaluate.getValue(context, parameter, String.class);
 		}
 		catch (Exception ex) {