in hadoop-api-shim/src/main/java/org/apache/hadoop/fs/shim/impl/FSDataInputStreamShimImpl.java [134:144]
public boolean hasCapability(final String capability) {
switch (toLowerCase(capability)) {
case PREADBYTEBUFFER:
// positioned read is always available
return true;
case READVECTORED:
return isVectorReadAvailable();
default:
return getInstance().hasCapability(capability);
}
}