[BUG] Static way of using Azure key vault

[michaelqi793]

Is your feature request related to a problem? Please describe.
A clear and concise description of what the problem is. Ex. I'm always frustrated when [...]
Every time I need use Azure key vault key store, for example, I want to program an https web client. I have to program like this:

 KeyStore azureKeyVaultKeyStore = KeyStore.getInstance("AzureKeyVault");
        KeyVaultLoadStoreParameter parameter = new KeyVaultLoadStoreParameter(
            System.getProperty("azure.keyvault.uri"),
            System.getProperty("azure.keyvault.tenant-id"),
            System.getProperty("azure.keyvault.client-id"),
            System.getProperty("azure.keyvault.client-secret"));
        azureKeyVaultKeyStore.load(parameter);
        SSLContext sslContext = org.apache.http.ssl.SSLContexts.custom()
                                           .loadTrustMaterial(azureKeyVaultKeyStore, null)
                                           .build();

This means 1 My code can only work with Azure key vault key store in runtime. 2 I have to code for Azure key vault. All are frustrating!

Describe the solution you'd like
A clear and concise description of what you want to happen.
My code has nothing to do with Azure key vault key store in development.
For example, the above code is changed to remain like this:

 SSLContext sslContext = org.apache.http.ssl.SSLContexts.custom()
                                           .loadTrustMaterial(null, null)
                                           .build();

This code can work with Azure key vault key store in runtime if I run my code via command line and add proper system properties via -D. So please support the static way of using Azure Key vault key store. Please refer to https://docs.oracle.com/javase/8/docs/technotes/guides/security/crypto/CryptoSpec.html#ProviderInstalling

Describe alternatives you've considered
A clear and concise description of any alternative solutions or features you've considered.
I tried to my code via command line to connect an https web server that uses key vault key store:
java --module-path ./azure-security-keyvault-jca-2.0.0-beta.1.jar --add-modules com.azure.security.keyvault.jca -Dsecurity.overridePropertiesFile=true -Djava.security.properties==./java.security -Djavax.net.ssl.trustStoreType=AzureKeyVault -Dazure.keyvault.uri=<mykeyvaultURI> -Dazure.keyvault.tenant-id=<myTeanantID> -Dazure.keyvault.client-id=<myClientID> -Dazure.keyvault.client-secret=<mySecretValue> MyCodeMainClass. But i got the following dead loop:

        ...
	at java.base/sun.security.ssl.SSLContextImpl.engineInit(SSLContextImpl.java:88)
	at java.base/javax.net.ssl.SSLContext.init(SSLContext.java:297)
	at com.azure.security.keyvault.jca@2.0.0-beta.1/com.azure.security.keyvault.jca.implementation.shaded.org.apache.http.ssl.SSLContexts.createDefault(SSLContexts.java:52)
	at com.azure.security.keyvault.jca@2.0.0-beta.1/com.azure.security.keyvault.jca.implementation.shaded.org.apache.http.impl.client.HttpClientBuilder.build(HttpClientBuilder.java:977)
	at com.azure.security.keyvault.jca@2.0.0-beta.1/com.azure.security.keyvault.jca.implementation.shaded.org.apache.http.impl.client.HttpClients.createDefault(HttpClients.java:56)
	at com.azure.security.keyvault.jca@2.0.0-beta.1/com.azure.security.keyvault.jca.implementation.utils.HttpUtil.post(HttpUtil.java:70)
	at com.azure.security.keyvault.jca@2.0.0-beta.1/com.azure.security.keyvault.jca.implementation.utils.HttpUtil.post(HttpUtil.java:53)
	at com.azure.security.keyvault.jca@2.0.0-beta.1/com.azure.security.keyvault.jca.implementation.utils.AccessTokenUtil.getAccessToken(AccessTokenUtil.java:107)
	at com.azure.security.keyvault.jca@2.0.0-beta.1/com.azure.security.keyvault.jca.implementation.KeyVaultClient.getAccessToken(KeyVaultClient.java:195)
	at com.azure.security.keyvault.jca@2.0.0-beta.1/com.azure.security.keyvault.jca.implementation.KeyVaultClient.getAliases(KeyVaultClient.java:215)
	at com.azure.security.keyvault.jca@2.0.0-beta.1/com.azure.security.keyvault.jca.implementation.certificates.KeyVaultCertificates.refreshCertificates(KeyVaultCertificates.java:142)
	at com.azure.security.keyvault.jca@2.0.0-beta.1/com.azure.security.keyvault.jca.implementation.certificates.KeyVaultCertificates.refreshCertificatesIfNeeded(KeyVaultCertificates.java:130)
	at com.azure.security.keyvault.jca@2.0.0-beta.1/com.azure.security.keyvault.jca.implementation.certificates.KeyVaultCertificates.getAliases(KeyVaultCertificates.java:100)
	at com.azure.security.keyvault.jca@2.0.0-beta.1/com.azure.security.keyvault.jca.KeyVaultKeyStore.getAllAliases(KeyVaultKeyStore.java:283)
	at com.azure.security.keyvault.jca@2.0.0-beta.1/com.azure.security.keyvault.jca.KeyVaultKeyStore.engineAliases(KeyVaultKeyStore.java:168)
	at java.base/java.security.KeyStore.aliases(KeyStore.java:1269)
	at java.base/sun.security.validator.TrustStoreUtil.getTrustedCerts(TrustStoreUtil.java:56)
	at java.base/sun.security.ssl.TrustStoreManager$TrustAnchorManager.loadTrustedCerts(TrustStoreManager.java:390)
	at java.base/sun.security.ssl.TrustStoreManager$TrustAnchorManager.getTrustedCerts(TrustStoreManager.java:321)
	at java.base/sun.security.ssl.TrustStoreManager.getTrustedCerts(TrustStoreManager.java:55)
	at java.base/sun.security.ssl.TrustManagerFactoryImpl.engineInit(TrustManagerFactoryImpl.java:49)
	at java.base/javax.net.ssl.TrustManagerFactory.init(TrustManagerFactory.java:278)
	at java.base/sun.security.ssl.SSLContextImpl.engineInit(SSLContextImpl.java:88)
	at java.base/javax.net.ssl.SSLContext.init(SSLContext.java:297)
        ...

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[michaelqi793]

Root cause found: the first sslcontext need instantiate trust manager which then instantiates AzureKeyVault and invokes the AzureKeyVault's getAliases, AzureKeyVault's getAliases then also needs ssl connection and instantiates sslcontext, hence a dead loop.