Implement maxAttempts inside the RetrySettings for GAPICs

[lqiu96]

RetrySettingsComposer doesn't have logic to create set the maxAttempts value:

sdk-platform-java/gapic-generator-java/src/main/java/com/google/api/generator/gapic/composer/common/RetrySettingsComposer.java

Lines 495 to 588 in 087253a

	private static List<Expr> createRetrySettingsExprs(
	String settingsName,
	GapicRetrySettings settings,
	VariableExpr settingsVarExpr,
	VariableExpr definitionsVarExpr) {
	Expr settingsBuilderExpr =
	MethodInvocationExpr.builder()
	.setStaticReferenceType(FIXED_TYPESTORE.get("RetrySettings"))
	.setMethodName("newBuilder")
	.build();
	RetryPolicy retryPolicy = settings.retryPolicy();
	if (settings.kind().equals(GapicRetrySettings.Kind.FULL)) {
	Preconditions.checkState(
	retryPolicy.hasInitialBackoff(),
	String.format("initialBackoff not found for setting %s", settingsName));
	settingsBuilderExpr =
	MethodInvocationExpr.builder()
	.setExprReferenceExpr(settingsBuilderExpr)
	.setMethodName("setInitialRetryDelay")
	.setArguments(createDurationOfMillisExpr(toValExpr(retryPolicy.getInitialBackoff())))
	.build();
	settingsBuilderExpr =
	MethodInvocationExpr.builder()
	.setExprReferenceExpr(settingsBuilderExpr)
	.setMethodName("setRetryDelayMultiplier")
	.setArguments(toValExpr(retryPolicy.getBackoffMultiplier()))
	.build();
	Preconditions.checkState(
	retryPolicy.hasMaxBackoff(),
	String.format("maxBackoff not found for setting %s", settingsName));
	settingsBuilderExpr =
	MethodInvocationExpr.builder()
	.setExprReferenceExpr(settingsBuilderExpr)
	.setMethodName("setMaxRetryDelay")
	.setArguments(createDurationOfMillisExpr(toValExpr(retryPolicy.getMaxBackoff())))
	.build();
	}
	if (!settings.kind().equals(GapicRetrySettings.Kind.NONE)) {
	settingsBuilderExpr =
	MethodInvocationExpr.builder()
	.setExprReferenceExpr(settingsBuilderExpr)
	.setMethodName("setInitialRpcTimeout")
	.setArguments(createDurationOfMillisExpr(toValExpr(settings.timeout())))
	.build();
	}
	// This will always be done, no matter the type of the retry settings object.
	settingsBuilderExpr =
	MethodInvocationExpr.builder()
	.setExprReferenceExpr(settingsBuilderExpr)
	.setMethodName("setRpcTimeoutMultiplier")
	.setArguments(
	ValueExpr.withValue(
	PrimitiveValue.builder().setType(TypeNode.DOUBLE).setValue("1.0").build()))
	.build();
	if (!settings.kind().equals(GapicRetrySettings.Kind.NONE)) {
	for (String setterMethodName : Arrays.asList("setMaxRpcTimeout", "setTotalTimeout")) {
	settingsBuilderExpr =
	MethodInvocationExpr.builder()
	.setExprReferenceExpr(settingsBuilderExpr)
	.setMethodName(setterMethodName)
	.setArguments(createDurationOfMillisExpr(toValExpr(settings.timeout())))
	.build();
	}
	}
	settingsBuilderExpr =
	MethodInvocationExpr.builder()
	.setExprReferenceExpr(settingsBuilderExpr)
	.setMethodName("build")
	.setReturnType(settingsVarExpr.type())
	.build();
	Expr settingsAssignExpr =
	AssignmentExpr.builder()
	.setVariableExpr(settingsVarExpr)
	.setValueExpr(settingsBuilderExpr)
	.build();
	Expr definitionsPutExpr =
	MethodInvocationExpr.builder()
	.setExprReferenceExpr(definitionsVarExpr)
	.setMethodName("put")
	.setArguments(
	ValueExpr.withValue(StringObjectValue.withValue(settingsName)), settingsVarExpr)
	.build();
	return Arrays.asList(settingsAssignExpr, definitionsPutExpr);
	}

even if it's set in the grpc_service.json file.

Searching through google-cloud-java shows that there aren't any occurrences of setMaxAttempts being generated in the StubSettings: https://github.com/search?q=repo%3Agoogleapis%2Fgoogle-cloud-java%20setMaxAttempts&type=code