Spring-boot Custom XML PropertySource

This project uses an external XML configuration file demo_config.xml. This is done by registering a SpringApplicationRunListener to read the XML configuration using apache commons configuration and adding the resultant PropertySource to the Environment. Properties are mapped to Rich Value objects using the @ConfigurationProperties annotation.

Spring delegates the getProperty() calls to the underlying apache commons configuration classes.

The XML configuration can refer to properties defined in application.properties and these placeholder's get expanded as expected.

Issue 1

environment.getProperty("demo.feature") returns a list of String with placeholders not expanded. environment.getProperty("demo.feature{1}) returns a String and has the placeholder expanded.

The end result of this issue is that Configuration value objects like DemoProperties that have configuration elements map to a List do not have the property placeholders within each item in the list resolved.

Example: demo.feature in demo_config.xml maps to a List<String> in DemoProperties

Second feature,Some feature in ${demo.version}

See DemoXmlConfigurationSource.addToEnvironment(...) for the issue.

Root Cause

Placeholders are only resolved for Strings as seen here:77

@Nullable
	protected <T> T getProperty(String key, Class<T> targetValueType, boolean resolveNestedPlaceholders) {
		if (this.propertySources != null) {
			for (PropertySource<?> propertySource : this.propertySources) {
				if (logger.isTraceEnabled()) {
					logger.trace("Searching for key '" + key + "' in PropertySource '" +
							propertySource.getName() + "'");
				}
				Object value = propertySource.getProperty(key);
				if (value != null) {
					if (resolveNestedPlaceholders && value instanceof String) {
						value = resolveNestedPlaceholders((String) value);
					}
					logKeyFound(key, propertySource, value);
					return convertValueIfNecessary(value, targetValueType);
				}
			}
		}
		if (logger.isDebugEnabled()) {
			logger.debug("Could not find key '" + key + "' in any property source");
		}
		return null;
	}

Fix

One fix is to autowire an Environment in DemoProperties.java Use Environment.resolvePlaceholders(...) to resolve each item in the List<String>.

 public List<String> getFeature() {
        return feature
                .parallelStream()
                .map(feature -> environment.resolvePlaceholders(feature))
                .collect(Collectors.toList());
    }

Issue 2

Mapping String to Instant in DemoProperties, an Invalid date string causes the following ConverterNotFoundException: No converter found capable of converting from type [java.lang.String] to type [java.time.Instant]:

org.springframework.validation.BindException: org.springframework.boot.bind.RelaxedDataBinder$RelaxedBeanPropertyBindingResult: 1 errors
Field error in object 'demo' on field 'endDateTime': rejected value [20080915T155300Z]; codes [typeMismatch.demo.endDateTime,typeMismatch.endDateTime,typeMismatch.java.time.Instant,typeMismatch]; arguments [org.springframework.context.support.DefaultMessageSourceResolvable: codes [demo.endDateTime,endDateTime]; arguments []; default message [endDateTime]]; default message [Failed to convert property value of type 'java.lang.String' to required type 'java.time.Instant' for property 'endDateTime'; nested exception is org.springframework.core.convert.ConverterNotFoundException: No converter found capable of converting from type [java.lang.String] to type [java.time.Instant]]
	at org.springframework.boot.bind.PropertiesConfigurationFactory.checkForBindingErrors(PropertiesConfigurationFactory.java:359) ~[spring-boot-1.5.6.RELEASE.jar:1.5.6.RELEASE]
	at org.springframework.boot.bind.PropertiesConfigurationFactory.doBindPropertiesToTarget(PropertiesConfigurationFactory.java:276) ~[spring-boot-1.5.6.RELEASE.jar:1.5.6.RELEASE]

This misleads the developer into thinking that the Converter has not been registered.

The problem in this case is that the following date string is an invalid ISO-8601 format:

<endDateTime>20080915T155300Z</endDateTime>

The fix is to correct the date String to:

<endDateTime>2008-09-15T15:53:00Z</endDateTime>

Issue 3

Included hive-jdbc.jar which pulls in 2 different jars that contain javax.el.ExpressionFactory but no implementation.

This then results in this error even though org.glassfish:javax.el:3.0.1-b08 is included as a dependency as mentioned in hibernate-validator getting started

javax.validation.ValidationException: HV000183: Unable to initialize 'javax.el.ExpressionFactory'. Check that you have the EL dependencies on the classpath, or use ParameterMessageInterpolator instead

	at org.hibernate.validator.messageinterpolation.ResourceBundleMessageInterpolator.buildExpressionFactory(ResourceBundleMessageInterpolator.java:122)
	at org.hibernate.validator.messageinterpolation.ResourceBundleMessageInterpolator.<init>(ResourceBundleMessageInterpolator.java:46)
	at org.hibernate.validator.internal.engine.ConfigurationImpl.getDefaultMessageInterpolator(ConfigurationImpl.java:420)
	at org.hibernate.validator.internal.engine.ConfigurationImpl.getDefaultMessageInterpolatorConfiguredWithClassLoader(ConfigurationImpl.java:596)
	at org.hibernate.validator.internal.engine.ConfigurationImpl.getMessageInterpolator(ConfigurationImpl.java:355)
	at org.hibernate.validator.internal.engine.ValidatorFactoryImpl.<init>(ValidatorFactoryImpl.java:149)
	at org.hibernate.validator.HibernateValidator.buildValidatorFactory(HibernateValidator.java:38)
	at org.hibernate.validator.internal.engine.ConfigurationImpl.buildValidatorFactory(ConfigurationImpl.java:322)
	at javax.validation.Validation.buildDefaultValidatorFactory(Validation.java:103)
	at com.configuration.config_demo.DemoPropertiesTest.setUp(DemoPropertiesTest.java:32)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)
	at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
	at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
	at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:24)

Brute force solution

Use the following to command to search through all dependencies to find all jars that contain javax.el.ExpressionFactory and exclude the ones that do not belong to org.glassfish:javax.el:3.0.1-b08

for i in $(mvn dependency:build-classpath | grep '.m2' | tr ':' ' '); do                                                                                                                                                               [19:14:33]
 jar -tvf $i | grep  'javax/el/ExpressionFactory' && echo -e "\t$i"
done  2> /dev/null