Background
Current client builders such as OtlpHttpSpanExporterBuilder provides operations (generally named setClientTls and setTrustredCertificates) for handling the mTLS certificates that takes only the raw pem files as byte array. The conversion of pem->key/trustores is then handled internally.

In some scenarios, the pem->trust/keystore conversion is handled externally, so ideally all clients should accept the already-built key/trustores.

Solution
Provide overloaded setClientTls and setTrustedCertificates methods for passing the *stores.

ps: Although this issue is referring specifically to OtlpHttpSpanExporterBuilder, a similar pattern is being followed by other classes that interacts with external nodes, hence this ideally should be fixed on all similar cases.