docs: update documentation to require certain fields

PiperOrigin-RevId: 530345646 Source-Link: googleapis/googleapis@ae157a1 Source-Link: googleapis/googleapis-gen@1798b3d Copy-Tag: eyJwIjoiamF2YS10ZXh0dG9zcGVlY2gvLk93bEJvdC55YW1sIiwiaCI6IjE3OThiM2QwYmQxNmM2ZmZjNmExY2NhMzFmMzE2Mjk0MjM0NzI3YmIifQ==
googleapis · gcf-merge-on-green · May 9, 2023 · May 8, 2023 · May 8, 2023 · May 8, 2023
commit e43bc5d369601f850be489f6bac6664d03eff0e0
diff --git a/...ospeech-v1beta1/src/main/java/com/google/cloud/texttospeech/v1beta1/TextToSpeechGrpc.java b/...ospeech-v1beta1/src/main/java/com/google/cloud/texttospeech/v1beta1/TextToSpeechGrpc.java
diff --git a/...ospeech-v1/src/main/java/com/google/cloud/texttospeech/v1/CustomVoiceParamsOrBuilder.java b/...ospeech-v1/src/main/java/com/google/cloud/texttospeech/v1/CustomVoiceParamsOrBuilder.java
diff --git a/.../src/main/java/com/google/cloud/texttospeech/v1/SynthesizeLongAudioResponseOrBuilder.java b/.../src/main/java/com/google/cloud/texttospeech/v1/SynthesizeLongAudioResponseOrBuilder.java