Issue: SPR-8348

Users may now call #setRequiredProperties(String...) against the
Environment (via its ConfigurablePropertyResolver interface) in order
to indicate which properties must be present.

Environment#validateRequiredProperties() is invoked by
AbstractApplicationContext during the refresh() lifecycle to perform
the actual check and a MissingRequiredPropertiesException is thrown
if the precondition is not satisfied.

Issue: SPR-8323

in AbstractApplicationContext and SpringContextResourceAdapter

* removed registerStandardBeanFactoryPostProcessors() methods
* removed commented-out test from PropertyResourceConfigurerTests

Decomposed Environment interface into PropertySources, PropertyResolver
objects

    Environment interface and implementations are still present, but
    simpler.

    PropertySources container aggregates PropertySource objects;
    PropertyResolver provides search, conversion, placeholder
    replacement. Single implementation for now is
    PropertySourcesPlaceholderResolver

Renamed EnvironmentAwarePropertyPlaceholderConfigurer to
PropertySourcesPlaceholderConfigurer

    <context:property-placeholder/> now registers PSPC by default, else
    PPC if systemPropertiesMode* settings are involved

Refined configuration and behavior of default profiles

    See Environment interface Javadoc for details

Added Portlet implementations of relevant interfaces:

    * DefaultPortletEnvironment
    * PortletConfigPropertySource, PortletContextPropertySource
    * Integrated each appropriately throughout Portlet app contexts

Added protected 'createEnvironment()' method to AbstractApplicationContext

    Subclasses can override at will to supply a custom Environment
    implementation.  In practice throughout the framework, this is how
    Web- and Portlet-related ApplicationContexts override use of the
    DefaultEnvironment and swap in DefaultWebEnvironment or
    DefaultPortletEnvironment as appropriate.

Introduced "stub-and-replace" behavior for Servlet- and Portlet-based
PropertySource implementations

    Allows for early registration and ordering of the stub, then
    replacement with actual backing object at refresh() time.

    Added AbstractApplicationContext.initPropertySources() method to
    support stub-and-replace behavior. Called from within existing
    prepareRefresh() method so as to avoid impact with
    ApplicationContext implementations that copy and modify AAC's
    refresh() method (e.g.: Spring DM).

    Added methods to WebApplicationContextUtils and
    PortletApplicationContextUtils to support stub-and-replace behavior

Added comprehensive Javadoc for all new or modified types and members

Added XSD documentation for all new or modified elements and attributes

    Including nested <beans>, <beans profile="..."/>, and changes for
    certain attributes type from xsd:IDREF to xsd:string

Improved fix for detecting non-file based Resources in
PropertiesLoaderSupport (SPR-7547, SPR-7552)

    Technically unrelated to environment work, but grouped in with
    this changeset for convenience.

Deprecated (removed) context:property-placeholder
'system-properties-mode' attribute from spring-context-3.1.xsd

    Functionality is preserved for those using schemas up to and including
    spring-context-3.0.  For 3.1, system-properties-mode is no longer
    supported as it conflicts with the idea of managing a set of property
    sources within the context's Environment object. See Javadoc in
    PropertyPlaceholderConfigurer, AbstractPropertyPlaceholderConfigurer
    and PropertySourcesPlaceholderConfigurer for details.

Introduced CollectionUtils.toArray(Enumeration<E>, A[])

Work items remaining for 3.1 M2:

    Consider repackaging PropertySource* types; eliminate internal use
    of SystemPropertyUtils and deprecate

    Further work on composition of Environment interface; consider
    repurposing existing PlaceholderResolver interface to obviate need
    for resolve[Required]Placeholder() methods currently in Environment.

    Ensure configurability of placeholder prefix, suffix, and value
    separator when working against an AbstractPropertyResolver

    Add JNDI-based Environment / PropertySource implementatinos

    Consider support for @Profile at the @Bean level

    Provide consistent logging for the entire property resolution
    lifecycle; consider issuing all such messages against a dedicated
    logger with a single category.

    Add reference documentation to cover the featureset.

Branch in question is 'env' branch from git://git.springsource.org/sandbox/cbeams.git; merged into
git-svn repository with:

    git merge -s recursive -Xtheirs --no-commit env

No merge conflicts, but did need to

    git rm spring-build

prior to committing.

With this change, Spring 3.1.0 development is now happening on SVN
trunk. Further commits to the 3.0.x line will happen in an as-yet
uncreated SVN branch.  3.1.0 snapshots will be available
per the usual nightly CI build from trunk.

refined LifecycleProcessor exception handling, properly wrapping a start exception from a bean (SPR-7106)

BeanDefinitionRegistryPostProcessors' postProcessBeanDefinitionRegistry() method now gets called before postProcessBeanFactory() (SPR-7167)

context-specific "conversionService" bean may refer to annotation-configured converter beans (SPR-6800)

introduced BeanDefinitionRegistryPostProcessor extension to BeanFactoryPostProcessor; @Configuration classes support definition of BeanFactoryPostProcessor beans as well (SPR-6455, SPR-6611)

removed getBeansWithAnnotation(Class,boolean,boolean) method from ListableBeanFactory; reimplemented getBeansWithAnnotation(Class) to avoid use of getBeanNamesForType(Object.class)

fixed LifecycleProcessor lookup in a Spring Dynamic Modules context (SPR-6356); moved ConversionService lookup to prepareBeanFactory

MergedBeanDefinitionPostProcessors apply after all other post-processors (for @PostConstruct to be invoked after other BPPs; SPR-6066)

SPR-6308 - Spring Expression Language creates systemProperties bean calling System.getProperties() which in enterprise shared containers is locked down

SPR-5507 Added SmartLifecycle interface with 'isAutoStartup' method and added an 'onRefresh' method to the LifecycleProcessor.

SPR-5507 Factored out Lifecycle management to a LifecycleProcessor strategy with the default implementation as DefaultLifecycleProcessor. The 'lifecycleProcessor' bean may be defined to override the default.

support for default "conversionService" bean in an ApplicationContext; revised formatting package, now integrated with DataBinder and AnnotationMethodHandlerAdapter; revised AccessControlContext access from BeanFactory

Servlet/Portlet ApplicationContexts use a specific id based on servlet/portlet name; DefaultListableBeanFactory references are serializable now when initialized with an id; scoped proxies are serializable now, for web scopes as well as for singleton beans; injected request/session references are serializable proxies for the current request now

revised support for annotated factory methods (merged @FactoryMethod functionality into JavaConfig facility)

ApplicationListener beans get obtained on demand, supporting non-singletons as well; ApplicationListeners will be called in the order according to the Ordered contract; generified ApplicationListener interface

EL container integration; support for contextual objects; removal of deprecated Spring 2.0 functionality; Java 5 code style