Strange Oracle XMLType.getClobVal() result

I use Oracle 11g (on Red Hat). I have simple regular table with XMLType column:

CREATE TABLE PROJECTS
(
  PROJECT_ID NUMBER(*, 0) NOT NULL,
  PROJECT SYS.XMLTYPE,
);

Using Oracle SQL Developer (on Windows) I do:

select T1.PROJECT P1 from PROJECTS T1 where PROJECT_ID = '161';

It works. I get one cell. I can double click and download whole XML file.

Then I tried to get result as CLOB:

select T1.PROJECT.getClobVal() P1 from PROJECTS T1 where PROJECT_ID = '161';

It works. I get one cell. I can double click and see whole text and copy it. BUT there is a problem. When I copy it to clipboard I get only first 4000 characters. It seems that there is 0x00 character at position 4000 and the rest of CLOB is not copied.

To confirm this, I wrote check in java:

// ... create projectsStatement
Reader reader = projectsStatement.getResultSet().getCharacterStream( "P1" );
BufferedReader bf = new BufferedReader( reader );
char buffer[] = new char[ 1024 ];
int count = 0;
int globalPos = 0;
while ( ( count = bf.read( buffer, 0, buffer.length ) ) > 0 )
    for ( int i = 0; i < count; i++, globalPos++ )
        if ( buffer[ i ] == 0 )
            throw new Exception( "ZERO at " + Integer.toString(globalPos) );

Reader returns full XML but my exception is thrown because there is null character at position 4000. I could remove this single byte but this would be rather strange workaround.

I don't use VARCHAR2 there but maybe this problem is related to VARCHAR2 limitation (4000 bytes) somehow ? Any other ideas ? Is this an Oracle bug or am I missing something ?

-------------------- Edit --------------------

Value was inserted using following stored procedure:

create or replace
procedure addProject( projectId number, projectXml clob ) is
  sqlstr varchar2(2000);
begin

  sqlstr := 'insert into pro