RFR: 8029370: (fc) FileChannel javadoc not clear for cases where position == size

[Brian Burkhalter]

Modify the specifications of the `java.nio.channels.FileChannel` methods `transferTo`, `read(ByteBuffer,long)`, and `write(ByteBuffer,long)` to state "greater than or equal to the file's current size" with respect to the given position instead of "greater than the file's current size."

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Commit messages:
 - 8029370: (fc) FileChannel javadoc not clear for cases where position == size

Changes: https://git.openjdk.org/jdk/pull/12735/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=12735&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8029370
  Stats: 4 lines in 1 file changed: 0 ins; 0 del; 4 mod
  Patch: https://git.openjdk.org/jdk/pull/12735.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/12735/head:pull/12735

PR: https://git.openjdk.org/jdk/pull/12735