Mention SystemEnvironmentPropertySource in related Javadoc

Issue: SPR-8869

org.springframework.core/src/main/java/org/springframework/core/env/AbstractEnvironment.java

@@ -53,13 +53,23 @@ import org.springframework.util.StringUtils;
 public abstract class AbstractEnvironment implements ConfigurableEnvironment {
 
 	/**
-	 * Name of property to set to specify active profiles: {@value}. May be comma delimited.
+	 * Name of property to set to specify active profiles: {@value}. Value may be comma
+	 * delimited.
+	 * <p>Note that certain shell environments such as Bash disallow the use of the period
+	 * character in variable names. Assuming that Spring's {@link SystemEnvironmentPropertySource}
+	 * is in use, this property may be specified as an environment variable as
+	 * {@code SPRING_PROFILES_ACTIVE}.
 	 * @see ConfigurableEnvironment#setActiveProfiles
 	 */
 	public static final String ACTIVE_PROFILES_PROPERTY_NAME = "spring.profiles.active";
 
 	/**
-	 * Name of property to set to specify default profiles: {@value}. May be comma delimited.
+	 * Name of property to set to specify profiles active by default: {@value}. Value may
+	 * be comma delimited.
+	 * <p>Note that certain shell environments such as Bash disallow the use of the period
+	 * character in variable names. Assuming that Spring's {@link SystemEnvironmentPropertySource}
+	 * is in use, this property may be specified as an environment variable as
+	 * {@code SPRING_PROFILES_DEFAULT}.
 	 * @see ConfigurableEnvironment#setDefaultProfiles
 	 */
 	public static final String DEFAULT_PROFILES_PROPERTY_NAME = "spring.profiles.default";

org.springframework.core/src/main/java/org/springframework/core/env/StandardEnvironment.java

@@ -41,6 +41,10 @@ package org.springframework.core.env;
  * instance available from {@link #getPropertySources()}. See
  * {@link ConfigurableEnvironment} Javadoc for usage examples.
  *
+ * <p>See {@link SystemEnvironmentPropertySource} Javadoc for details on special handling
+ * of property names in shell environments (e.g. Bash) that disallow period characters in
+ * variable names.
+ *
  * @author Chris Beams
  * @since 3.1
  * @see ConfigurableEnvironment