plot → expression Relation

File in src/core/plot	Includes file in src/core/expression
qgsbarchartplot.cpp	qgsexpressioncontextutils.h
qgslinechartplot.cpp	qgsexpressioncontextutils.h
qgspiechartplot.cpp	qgsexpressioncontextutils.h
qgsplot.cpp	qgsexpressioncontextutils.h
qgsvectorlayerplotdatagatherer.cpp	qgsexpression.h