Fix documentation for TreeToString - the correct replacement method is VisitorState#getConstantExpression
Fix documentation for TreeToString - the correct replacement method is VisitorState#getConstantExpression

PiperOrigin-RevId: 370708449

google/error-prone,cushon/error-prone,cushon/error-prone,cushon/error-prone,google/error-prone,cushon/error-prone