BaggageFields (Brave 5.13.9 API)

java.lang.Object
- brave.baggage.BaggageFields

```
public final class BaggageFields
extends Object
```
This contains pre-defined fields, such as TRACE_ID and a way to create a constant field.
Built-in fields
The following are fields that dispatch to methods on the TraceContext. They are available regardless of BaggagePropagation. None will return in lookups such as BaggageField.getAll(TraceContext) or BaggageField.getByName(TraceContext, String)
Since:

5.11

Field Summary

Fields
Modifier and Type	Field	Description
`static BaggageField`	`PARENT_ID`	Typically only useful when spans are parsed from log records.
`static BaggageField`	`SAMPLED`	This is only useful when `TRACE_ID` is also a baggage field.
`static BaggageField`	`SPAN_ID`	Used with `TRACE_ID` to correlate a log line with a span.
`static BaggageField`	`TRACE_ID`	This is the most common log correlation field.

Constructor Summary

Constructors
Constructor Description

BaggageFields()

Method Summary

All Methods Static Methods Concrete Methods
Modifier and Type	Method	Description
`static BaggageField`	`constant(String name, String value)`	Creates a local baggage field based on a possibly null constant, such as an ENV variable.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Field Detail
  - TRACE_ID
```
public static final BaggageField TRACE_ID
```
    This is the most common log correlation field.
    
    Since:
    
    5.11
    
    See Also:
    
    TraceContext.traceIdString()
  - PARENT_ID
```
public static final BaggageField PARENT_ID
```
    Typically only useful when spans are parsed from log records.
    
    Since:
    
    5.11
    
    See Also:
    
    TraceContext.parentIdString()
  - SPAN_ID
```
public static final BaggageField SPAN_ID
```
    Used with TRACE_ID to correlate a log line with a span.
    
    Since:
    
    5.11
    
    See Also:
    
    TraceContext.spanIdString()
  - SAMPLED
```
public static final BaggageField SAMPLED
```
    This is only useful when TRACE_ID is also a baggage field. It is a hint that a trace may exist in Zipkin, when a user is viewing logs. For example, unsampled traces are not typically reported to Zipkin.
    
    Since:
    
    5.11
    
    See Also:
    
    SamplingFlags.sampled()
- Constructor Detail
  - BaggageFields
```
public BaggageFields()
```
- Method Detail
  - constant
```
public static BaggageField constant(String name,
                                    @Nullable
                                    String value)
```
    Creates a local baggage field based on a possibly null constant, such as an ENV variable.
    Ex.
    CLOUD_REGION = BaggageFields.constant("region", System.getEnv("CLOUD_REGION"));
    Since:
    
    5.11