core/src/main/java/org/springframework/security/authentication/jaas/JaasAuthenticationProvider.java
@Override
	public void afterPropertiesSet() throws Exception {
		// the superclass is not called because it does additional checks that are
		// non-passive
		Assert.hasLength(getLoginContextName(),
				() -> "loginContextName must be set on " + getClass());
		Assert.notNull(this.loginConfig,
				() -> "loginConfig must be set on " + getClass());
		configureJaas(this.loginConfig);

		Assert.notNull(Configuration.getConfiguration(),
				"As per https://java.sun.com/j2se/1.5.0/docs/api/javax/security/auth/login/Configuration.html "
						+ "\"If a Configuration object was set via the Configuration.setConfiguration method, then that object is "
						+ "returned. Otherwise, a default Configuration object is returned\". Your JRE returned null to "
						+ "Configuration.getConfiguration().");
	}
@Override
	public void afterPropertiesSet() throws Exception {
		// the superclass is not called because it does additional checks that are
		// non-passive
		Assert.hasLength(getLoginContextName(),
				() -> "loginContextName must be set on " + getClass());
		Assert.notNull(this.loginConfig,
				() -> "loginConfig must be set on " + getClass());
		configureJaas(this.loginConfig);

		Assert.notNull(Configuration.getConfiguration(),
				"As per https://java.sun.com/j2se/1.5.0/docs/api/javax/security/auth/login/Configuration.html "
						+ "\"If a Configuration object was set via the Configuration.setConfiguration method, then that object is "
						+ "returned. Otherwise, a default Configuration object is returned\". Your JRE returned null to "
						+ "Configuration.getConfiguration().");
	}
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