Fix grammar in JavaDoc for fully qualified links

This commit represents a best effort attempt at fixing remaining
"a" vs. "an" grammatical errors related links specified via a fully
qualified class name.

Issue: SPR-17208

spring-beans/src/main/java/org/springframework/beans/factory/config/DependencyDescriptor.java

@@ -335,7 +335,7 @@ public class DependencyDescriptor extends InjectionPoint implements Serializable
 	/**
 	 * Return whether a fallback match is allowed.
 	 * <p>This is {@code false} by default but may be overridden to return {@code true} in order
-	 * to suggest to a {@link org.springframework.beans.factory.support.AutowireCandidateResolver}
+	 * to suggest to an {@link org.springframework.beans.factory.support.AutowireCandidateResolver}
 	 * that a fallback match is acceptable as well.
 	 * @since 4.0
 	 */

spring-web/src/main/java/org/springframework/web/context/support/GroovyWebApplicationContext.java

@@ -33,7 +33,7 @@ import org.springframework.lang.Nullable;
 /**
  * {@link org.springframework.web.context.WebApplicationContext} implementation which takes
  * its configuration from Groovy bean definition scripts and/or XML files, as understood by
- * an {@link org.springframework.beans.factory.groovy.GroovyBeanDefinitionReader}.
+ * a {@link org.springframework.beans.factory.groovy.GroovyBeanDefinitionReader}.
  * This is essentially the equivalent of
  * {@link org.springframework.context.support.GenericGroovyApplicationContext}
  * for a web environment.

spring-webmvc/src/main/java/org/springframework/web/servlet/config/annotation/WebMvcConfigurationSupport.java

@@ -157,7 +157,7 @@ import org.springframework.web.util.UrlPathHelper;
  * <ul>
  * <li>a {@link ContentNegotiationManager}
  * <li>a {@link DefaultFormattingConversionService}
- * <li>a {@link org.springframework.validation.beanvalidation.OptionalValidatorFactoryBean}
+ * <li>an {@link org.springframework.validation.beanvalidation.OptionalValidatorFactoryBean}
  * if a JSR-303 implementation is available on the classpath
  * <li>a range of {@link HttpMessageConverter HttpMessageConverters} depending on the third-party
  * libraries available on the classpath.