Add tests for SpEL on Kotlin suspending function parameters

This was broken at some point but seems to work now.
This commit adds related tests.

Closes gh-26867

spring-expression/src/test/kotlin/org/springframework/expression/spel/KotlinSpelReproTests.kt

@@ -1,9 +1,26 @@
+/*
+ * Copyright 2002-2023 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
 package org.springframework.expression.spel
 
 import org.assertj.core.api.Assertions.assertThat
 import org.junit.jupiter.api.Test
 import org.springframework.expression.ExpressionParser
 import org.springframework.expression.spel.standard.SpelExpressionParser
+import kotlin.coroutines.Continuation
 
 class KotlinSpelReproTests {
 
@@ -18,11 +35,40 @@ class KotlinSpelReproTests {
 		assertThat(expr.getValue(context)).isEqualTo("test")
 	}
 
+	@Test
+	fun `gh-26867 SpEL can process Kotlin regular function parameter`() {
+		val expr = parser.parseExpression("#key.startsWith('hello')")
+		context.registerFunction("get", Config::class.java.getMethod("get", String::class.java))
+		context.setVariable("key", "hello world")
+		assertThat(expr.getValue(context, Boolean::class.java)).isTrue()
+		context.setVariable("key", "")
+		assertThat(expr.getValue(context, Boolean::class.java)).isFalse()
+	}
+
+	@Test
+	fun `gh-26867 SpEL can process Kotlin suspending function parameter`() {
+		val expr = parser.parseExpression("#key.startsWith('hello')")
+		context.registerFunction("suspendingGet", Config::class.java.getMethod("suspendingGet", String::class.java, Continuation::class.java))
+		context.setVariable("key", "hello world")
+		assertThat(expr	.getValue(context, Boolean::class.java)).isTrue()
+		context.setVariable("key", "")
+		assertThat(expr.getValue(context, Boolean::class.java)).isFalse()
+	}
+
+	@Suppress("UNUSED_PARAMETER")
 	class Config {
 
 		fun kotlinSupplier(): () -> String {
 			return { "test" }
 		}
 
+		fun get(key: String): Any {
+			throw NotImplementedError()
+		}
+
+		suspend fun suspendingGet(key: String) {
+			throw NotImplementedError()
+		}
+
 	}
 }