FULL PRODUCT VERSION :
java version "1.6.0_21"
Java(TM) SE Runtime Environment (build 1.6.0_21-b07)
Java HotSpot(TM) 64-Bit Server VM (build 17.0-b17, mixed mode)

ADDITIONAL OS VERSION INFORMATION :
Microsoft Windows [Version 6.1.7601]

A DESCRIPTION OF THE PROBLEM :
The following unit test snippet fails as is:

// a) InputStream is = new FileInputStream(f1);
InputStream is = new GZIPInputStream(new FileInputStream(f1));
try {
do {
//Skip
if (is.available() > 0) {
assertTrue(is.read() != -1);
} else {
assertTrue(is.read() == -1);
assertTrue(is.available() == 0);
break;
}

} while (true);

} finally {
is.close();
}

If we uncomment a) and comment the line after it, the test passes.
1) This hints a possible inconsistency between the input stream and the gzip-wrapped input stream.
2) According to the documentation, when available() tells we have something to take it returns a non-zero value, and a subsequent read() gives a byte from that something. This seems broken at the end of gzipped streams.

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Run the unit test, completing it with supplying a gzipped file.

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
Test passes.
ACTUAL -
Test fails.

ERROR MESSAGES/STACK TRACES THAT OCCUR :
Test fails at
assertTrue(is.read() != -1);

REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
@Test
public final void testGzippedStreamAPIConsistency() throws IOException {
File f1 = new File("bla01.gz");
writeOperationsZipFile(f1, 20);

// a) InputStream is = new FileInputStream(f1);
InputStream is = new GZIPInputStream(new FileInputStream(f1));
try {
do {
//Skip
if (is.available() > 0) {
assertTrue(is.read() != -1);
} else {
assertTrue(is.read() == -1);
assertTrue(is.available() == 0);
break;
}

} while (true);

} finally {
is.close();
}
}

private void writeOperationsZipFile(File f, final int howMany) throws IOException {
OutputStream fos = new GZIPOutputStream(new FileOutputStream(f));
try {
writeOutputStream(fos, howMany);
} finally {
fos.close();
}
}
private void writeOutputStream(OutputStream fos, int howMany) {
PrintStream ps = new PrintStream(fos);

try {
int i = 0;
while (i < howMany) {
//write an operation.
ps.println("operation" + i);
i++;
}//while
} finally {
ps.close();
}
}

---------- END SOURCE ----------

CUSTOMER SUBMITTED WORKAROUND :
Do not rely on available() but on the return result of read().