Partial Type

src/runtime/src/libraries/System.Private.CoreLib/src/System/Buffers/Text/Base64Decoder.cs

src/runtime/src/libraries/System.Private.CoreLib/src/System/Buffers/Text/Base64Encoder.cs

src/runtime/src/libraries/System.Private.CoreLib/src/System/Buffers/Text/Base64Validator.cs