Fix warnings in spring-boot-autoconfigure's Kotlin test code

Closes gh-19877

spring-boot-project/spring-boot-autoconfigure/src/test/kotlin/org/springframework/boot/autoconfigure/diagnostics/analyzer/KotlinNoSuchBeanFailureAnalyzerNoKotlinReflectTests.kt

@@ -29,9 +29,9 @@ class KotlinNoSuchBeanFailureAnalyzerNoKotlinReflectTests {
 		val analysis = analyzeFailure(
 				createFailure(ConstructorBoundConfigurationPropertiesConfiguration::class.java))
 		assertThat(analysis!!.getAction()).startsWith(
-				java.lang.String.format("Consider defining a bean of type '%s' in your configuration.", String::class.java!!.getName()))
-		assertThat(analysis!!.getAction()).contains(java.lang.String.format(
-				"Consider adding a dependency on kotlin-reflect so that the constructor used for @ConstructorBinding can be located. Also, ensure that @ConstructorBinding is present on '%s' ", ConstructorBoundProperties::class.java!!.getName()))
+				java.lang.String.format("Consider defining a bean of type '%s' in your configuration.", String::class.java.getName()))
+		assertThat(analysis.getAction()).contains(java.lang.String.format(
+				"Consider adding a dependency on kotlin-reflect so that the constructor used for @ConstructorBinding can be located. Also, ensure that @ConstructorBinding is present on '%s' ",ConstructorBoundProperties::class.java.getName()))
 	}
 
 	private fun createFailure(config: Class<*>, vararg environment: String): FatalBeanException? {